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/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Adjusting stock carb with modified engine /cgi-bin/YaBB.pl?num=1497282100 Message started by kojones on 06/12/17 at 08:41:39 |
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Title: Adjusting stock carb with modified engine Post by kojones on 06/12/17 at 08:41:39 The engine has a DR cam shaft, 95mm Wiseco, K&N and a HD muffler with one baffle, exhaust port mod done, too. The jets in the carb are now 160 main and a 55 pilot, replacing the main with a 165 when I get one. I took the carb open and I'm just trying to remove the idle mixture screw to replace that with a new one. The motor is not yet broke in, so I've never twisted the throttle over 1/4, so just looking for a starting point to get the mixture about right. It runs fine, with a fair amount of popping and backfire. What to do with the needle? Mine has three grooves and the spacer is the stock thick one. Any suggestions? Thanks in advance! |
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Title: Re: Adjusting stock carb with modified engine Post by Dave on 06/12/17 at 09:33:42 By US standards that is far richer than you should need to jet - but I have no idea what your fuel requires over there. |
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Title: Re: Adjusting stock carb with modified engine Post by Ruttly on 06/12/17 at 10:17:23 You put all that money in the engine , if you want easy tuning and real good throttle response you should sell the stock carb and buy the mikuni vm36 kit from Lancer here in the Market Place. You will not be disappointed. Trust me on this one you will thank me later ! |
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Title: Re: Adjusting stock carb with modified engine Post by kojones on 06/12/17 at 11:30:51 5C676A7D6C607B7D666E637C0F0 wrote:
You think so? That DR cam isn't the mildest option. |
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Title: Re: Adjusting stock carb with modified engine Post by kojones on 06/12/17 at 11:32:45 6A4D4C4C5441380 wrote:
That might be my next step, I'm now struggling to get the remains of the idle mixture screw out of the carb >:( Unfortunately shipping from US is so expensive that buying from Lancer isn't very cost effective way to get that carb. Got the remains out without destroying the carb body, so no need for VM36 just yet ;D |
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Title: Re: Adjusting stock carb with modified engine Post by verslagen1 on 06/12/17 at 13:10:56 787C797C7D7660130 wrote:
You think so? That DR cam isn't the mildest option.[/quote] The cam just lets it breathe, the fuel mixture shouldn't be any different from a stock engine with the same intake and exhaust. In the end you still need 12 to 14 a/f |
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Title: Re: Adjusting stock carb with modified engine Post by batman on 06/12/17 at 17:05:13 I'm with Dave and Verslagen ,I don't think you need bigger jets for more fuel/less air ,but you may need better fuel,( higher octane ) due to higher compression. |
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Title: Re: Adjusting stock carb with modified engine Post by kojones on 06/13/17 at 00:16:36 766572736C6167656E31000 wrote:
You think so? That DR cam isn't the mildest option.[/quote] The cam just lets it breathe, the fuel mixture shouldn't be any different from a stock engine with the same intake and exhaust. In the end you still need 12 to 14 a/f[/quote] Makes sense. The pilot jet seems to be quite sufficient, won't idle without choke when cold. Could also be a bit lean. How about the needle, half the spacer recommended? |
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Title: Re: Adjusting stock carb with modified engine Post by Dave on 06/13/17 at 02:42:48 If you have an adjustable needle, you may just be able to move the clip to raise the needle and not have to trim the spacer. I took my spacer out and put in 3 number 4 machine washers. Most of the time that works fine - my Savage still had a lean surge when applying light throttle, and taking out 1 washer got rid of it. With a Stage 1 cam, 95mm Wiseco, stock paper air filter and a Dyna muffler my carb was happy with a 150 main and a #50 pilot and 2 washers.....I ride between 500' and 800' elevation. The other bike I jetted was stock with a DYNA muffler and it wanted a #52.5 pilot and it was OK with 3 washers and it never had the lean surge (we do have 10% ethanol in our fuel). |
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Title: Re: Adjusting stock carb with modified engine Post by kojones on 06/13/17 at 06:28:51 63585542535F444259515C43300 wrote:
I had a 150/50 with the stock muffler and it worked fine, but after the Dyna installation it was seriously lean. Approx 300' from sea level. I use the E5, which has 5% ethanol. I think the the E10 isn't recommended with a high compression piston. Going to move the clip to lowest groove, we'll see how that affects the midrange. Removing the idle mixture screw was a nerve wrecking operation, came out in three separate parts :D Still have to open some threads when I get a M6x0.5 tap. |
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Title: Re: Adjusting stock carb with modified engine Post by Dave on 06/13/17 at 06:41:19 393D383D3C3721520 wrote:
We really don't have much of a choice of how much ethanol is in our fuel in the area I live in - the government mandate int the US is to reduce the dependency on foreign oil and the current way to do that is by adding 10% ethanol. If you are going to be riding your motorcycle on trips - you need to jet your carb for the gas that is available - we have to jet for the E10 that is available everywhere that we might be riding. Ethanol has a higher octane rating than gasoline and doesn't haven any problems with the 10.5 to 1 Wiseco pistons. Ethanol in higher concentrations than 10% is not approved for use in any motorcycle that I know of....and we would all be happiest if the darn stuff would just go away and we could buy 100% gasoline!! |
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Title: Re: Adjusting stock carb with modified engine Post by LANCER on 06/13/17 at 06:46:13 797D787D7C7761120 wrote:
I had a 150/50 with the stock muffler and it worked fine, but after the Dyna installation it was seriously lean. Approx 300' from sea level. I use the E5, which has 5% ethanol. I think the the E10 isn't recommended with a high compression piston. Going to move the clip to lowest groove, we'll see how that affects the midrange. Removing the idle mixture screw was a nerve wrecking operation, came out in three separate parts :D Still have to open some threads when I get a M6x0.5 tap.[/quote] Did the spring, washer & o-ring come out as well ? |
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Title: Re: Adjusting stock carb with modified engine Post by kojones on 06/13/17 at 06:51:31 5F64697E6F63787E656D607F0C0 wrote:
We really don't have much of a choice of how much ethanol is in our fuel in the area I live in - the government mandate int the US is to reduce the dependency on foreign oil and the current way to do that is by adding 10% ethanol. If you are going to be riding your motorcycle on trips - you need to jet your carb for the gas that is available - we have to jet for the E10 that is available everywhere that we might be riding. Ethanol has a higher octane rating than gasoline and doesn't haven any problems with the 10.5 to 1 Wiseco pistons. Ethanol in higher concentrations than 10% is not approved for use in any motorcycle that I know of....and we would all be happiest if the darn stuff would just go away and we could buy 100% gasoline!! [/quote] We also have the E85, which is all ethanol. Wonder how that would work, maybe I'll have to try :D I've read about some starting problems in winter, but the jetting isn't that difficult to adjust ;) |
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Title: Re: Adjusting stock carb with modified engine Post by Dave on 06/13/17 at 07:02:42 E85 will corrode anything that is aluminum and dissolve most rubber that wasn't designed to be used with ethanol. |
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Title: Re: Adjusting stock carb with modified engine Post by kojones on 06/13/17 at 11:22:25 3E333C3137206065520 wrote:
Yes. |
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Title: Re: Adjusting stock carb with modified engine Post by Gary_in_NJ on 06/13/17 at 12:08:24 kojones, Do you have the same model carb as we use in the US? Even in the US there are two versions of the Mikuni BS40SS that use different needle profiles. |
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Title: Re: Adjusting stock carb with modified engine Post by kojones on 06/13/17 at 21:00:34 4B41454F444D49401E181C2C0 wrote:
It's a BS40 for sure, but I'm not sure if it's a SS. Stock jetting was 47,5/127,5. |
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Title: Re: Adjusting stock carb with modified engine Post by kojones on 06/14/17 at 22:54:24 It's definately running rich now after lifting the needle, have to move the lock ring back to the center groove. Threads on the idle mixture screw hole are busted, think I'll have to buy and rebuild another carb, the Mikuni VM36 can wait for winter ;) |
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Title: Re: Adjusting stock carb with modified engine Post by justin_o_guy2 on 06/15/17 at 01:14:58 Try a tap and die. Hmm, didn't sound so hateful in my head, but it sure looks bad in print. |
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Title: Re: Adjusting stock carb with modified engine Post by kojones on 06/15/17 at 01:26:58 0A151314090E3F0F3F07151952600 wrote:
;D I have a tap, but no die. The screw is one turn out and glued in place. Got another carb for cheap already. |
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Title: Re: Adjusting stock carb with modified engine Post by kojones on 06/16/17 at 00:52:16 Strange behavior after carb rebuild, the bike starts fine without a choke when cold but pulling the choke one notch on idle raises the rpm's significantly. Twisting the throttle from idle and releasing it gives a black puff. After engine braking the idle gets low for a few seconds when warm, then raises to normal. Mid range feels fine, needle in the center slot with the original spacer. New needle and needle jet, otherwise same jets than before. Feels rich, but really isn't? :D |
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Title: Re: Adjusting stock carb with modified engine Post by batman on 06/16/17 at 06:28:59 Sounds like the idle jet may be to large ,and the mix screw is in to far.when you chop the throttle the rpm drops ,and when you pull out the choke the idle speed goes up(mix screw in to far).Twisting the throttle from idle your getting black smoke (pilot jet to large).You have to remember that there are two paths for fuel coming from the idle jet and the mix screw sets in one the other is unblocked,when you blip the throttle vacuum increases pulling more fuel into the carb ,and there is a delay before the side opens ,if the idle jet is to large you'll be very rich ,(your puff of black smoke).Ithink you said your running a 55 pilot ,standard here is 52.5 ,and stock setting for the mix screw is three turns out, but I think 1 1/2 to 2 1/2 would be good for you.I think you said you were at 1 turn that sounds to lean and is why your rpm is sagging when you close the throttle. |
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Title: Re: Adjusting stock carb with modified engine Post by verslagen1 on 06/16/17 at 07:18:15 3330253C303F6569510 wrote:
The initial set point for the idle mix is 1 1/2 turns out, at 3 turns you wanna go up a jet, 0, down. |
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Title: Re: Adjusting stock carb with modified engine Post by LANCER on 06/16/17 at 07:33:51 34303530313A2C5F0 wrote:
No choke required when cold ... pull choke rpm increases...black smoke...TOO RICH So what are the pilot/main jets, pilot screw setting, and needle setting you have now ? |
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Title: Re: Adjusting stock carb with modified engine Post by batman on 06/16/17 at 19:55:43 The fact that we don't know what jet needle /needle jet you used ,or if we are even familiar with that type, and the DR cam which we don't use because we think it might be a bit to radical for the S-40 makes it hard to advise what jets you need to use . The fact that you jumped from a 47.5 to a 55 pilot (3-steps) and a 127.5 main to a 155 (11-steps) seems to me a bit drastic,even with the larger piston and cam ,it may have been better to move up jet sizes in stags. You are going to get a lot of fuel just by the fact of the piston size ,if the cam has to high a lift ,(opening the valves more than 25% of their diameter) and you've "closed the centers " to much (a to long a valve overlap ) you may have a hard time sorting out your jetting .good luck! |
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Title: Re: Adjusting stock carb with modified engine Post by LANCER on 06/17/17 at 06:00:36 Look up the stock jetting on the carb used on the old DR650's. I just don't remember off hand, but it is a Mikuni CV type carb very similar to ours and is also a 40mm. I cannot remember for sure but it seems like it uses the same type of jets as well. Anyway, that will give you a place to start. Remember though, that the DR head has very nice straight exhaust ports, so with our crooked exhaust ports I would expect that the jetting requirements would be slightly less than the stock DR...or at least somewhere between the 2 stock carbs. |
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Title: Re: Adjusting stock carb with modified engine Post by kojones on 06/18/17 at 06:35:22 565B54595F48080D3A0 wrote:
160/55, needle clip in the center groove, pilot screw one turn out. Slips off the threads when 1'5 turns out. Went on a 200 km trip, got some problems at first 80 km's that felt like the needle was sticking, after that ran like it should. 50 mpg. |
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Title: Re: Adjusting stock carb with modified engine Post by batman on 06/18/17 at 18:14:16 Kojones, you never told us what air filter your running ,if your running a K&N or similar an you oiled it, it's likely some of that oil ended up on your carb slide at first ,making it stick slightly ,before moving on.(normal) |
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Title: Re: Adjusting stock carb with modified engine Post by kojones on 06/20/17 at 08:13:51 0102170E020D575B630 wrote:
It is a K&N indeed, in the stock airbox. I don't think it's that, just found my bike in a middle of a pond of gasoline, I drove it an hour ago and thought that the needle is sticking again. Didn't remember to turn the petcock to off position... Time to drain the oil, luckily it's already been there for 1000 km's and a friend bought a van :D |
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Title: Re: Adjusting stock carb with modified engine Post by batman on 06/20/17 at 09:35:00 Do you have a stock petcock ?or is the float valve sticking ,or the level in the float bowl set to high? If you have gas in your oil,you may want to check your air filter and air box drain too. |
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Title: Re: Adjusting stock carb with modified engine Post by kojones on 06/22/17 at 08:19:18 77746178747B212D150 wrote:
I've changed to a Raptor. I replaced the oil and polished the inside surface of the float valve, still seems a bit rich but will not run without choke when cold. I think I had a #50 pilot somewhere which was fine before the HD muffler, would've tried that one if I'd find it, but no luck. Throttle response is fine, still some black smoke when releasing the throttle. I measured the float level when I rebuilt the carb, was within some specs I found here. Here's the current situation: |
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Title: Re: Adjusting stock carb with modified engine Post by justin_o_guy2 on 06/22/17 at 08:29:53 Is that tube touching the carb? |
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Title: Re: Adjusting stock carb with modified engine Post by kojones on 06/22/17 at 08:34:23 5D4244435E5968586850424E05370 wrote:
Yes. |
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Title: Re: Adjusting stock carb with modified engine Post by justin_o_guy2 on 06/22/17 at 14:06:22 Your float Could be higher, but I don't know how it being set a bit low would affect the performance. BUT! If there IS a reason, someone will post it. |
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Title: Re: Adjusting stock carb with modified engine Post by batman on 06/22/17 at 14:27:14 Float level should be at the seam between the float bowl and the carb body ,it's low. Stock jetting for the old DR650 is 52.5 pilot and 137.5 main ,that's why I think your 55 /155 is to big , 52.5 /150 may be a better starting point. |
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Title: Re: Adjusting stock carb with modified engine Post by verslagen1 on 06/22/17 at 14:49:34 should be... http://suzukisavage.com/yabb2.2/Attachments/IMG_0495.JPG Lower makes it leaner. |
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Title: Re: Adjusting stock carb with modified engine Post by justin_o_guy2 on 06/22/17 at 18:18:52 Is there a Readers Digest Explanation for why it's leaner? |
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Title: Re: Adjusting stock carb with modified engine Post by batman on 06/22/17 at 19:09:48 yes ,I'm also trying to figure out how lower makes it leaner. |
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Title: Re: Adjusting stock carb with modified engine Post by verslagen1 on 06/22/17 at 19:17:31 No, but there's Bernoullis Principle... http://suzukisavage.com/cgi-bin/YaBB.pl?num=1497304045 Fluid mechanics... https://en.wikipedia.org/wiki/Fluid_mechanics And... versypedia! The gas, she gotta go up a little further. The further she gotta go, the less she will go. If you give her a boost, she be fat and you be happy. |
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Title: Re: Adjusting stock carb with modified engine Post by batman on 06/22/17 at 21:08:13 Vercy ,I think that's a stretch,the fuel in the bowl ,with it's straight sides has the same surface pressure (14.7psi)and the same surface area,. at it's present level as it does if the level was correct. and the carb is pulling the same vacuum.the difference in flow would be immeasurable .for example if you had a pipe 100 ft tall filled with water the pressure at the bottom would be about 60psi,the pressure 1/4 of an inch down would be 14.712psi ,so the difference in height in the level is twelve thousands of a pound ,and gas is lighter than water so will be even less. |
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Title: Re: Adjusting stock carb with modified engine Post by verslagen1 on 06/22/17 at 22:37:29 don't ask me then... go do it. |
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Title: Re: Adjusting stock carb with modified engine Post by Dave on 06/23/17 at 02:25:53 7D7E6B727E712B271F0 wrote:
Adjusting the float level on the Savage isn't necessary on a stock motor with stock air cleaner and exhaust - the factory setting work just fine. Adjusting the float level is however a common tuning practice on the CV carb, and the procedure is listed in most tuning guides for CV carbs. Here is a quote from the Factory Pro jetting guide: To get best low-end power, set float height (fuel level) so that the engine will accept full throttle, without missing or stumbling, in 2nd gear from 1500 to 2000 rpm at minimum. Float heights, unless otherwise specified in the installation guide, are measured from the "gasket surface" of the carb body to the highest part of the top of the float - with the float tang touching but not compressing the float valve spring. If the engine has a "wet" rhythmic, soggy area at full throttle / 1500 to 2000, that gets worse as the engine heats up, lower the fuel level by resetting the float height 1mm greater (if the original was 13mm - go to 14mm). This will lower the fuel level, making full throttle / 1500 to 2000 leaner. If the engine is "dry" and flat between 1500 to 2000 rpm, raise the fuel level. http://factorypro.com/tech/tech_tuning_procedures/tuning_carbtune,CV,lower_rpm_engines.html It should be noted that this adjustment is for "full throttle" use at low rpm - the float level adjustment doesn't have a lot of affect for the idle circuit. (The situation where the float level has the most affect is when the throttle butterfly is fully open and the slide is only being partially opened by the engine vacuum). |
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Title: Re: Adjusting stock carb with modified engine Post by justin_o_guy2 on 06/23/17 at 20:30:41 What part of Readers Digest do you smart people not get? I Think I got Lower is leaner.. I'm thinking I am lean already. Not bad,just enough to make less power at the top. Izzat possible? |
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Title: Re: Adjusting stock carb with modified engine Post by batman on 06/25/17 at 11:43:50 Dave,I don't really know if my bike has a "WET " OR "DRY" rhythmic area in 2nd gear @ 1500 to 2000 rpm ,@ 11 to 17 mph I'm not in 2nd gear or trying to go to wide open throttle,nor do I think I could feel the difference lugging the motor that badly.Where this may apply to four cylinder race bikes I don't think you could use this tuning method on our thumpers . The pro was talking about float heights of 13-14 mm our float heigths range from 26.4 -29.4 mm ,I think we're talking apples and oranges here.Have you ever really used this method to set a CV carb? |
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Title: Re: Adjusting stock carb with modified engine Post by kojones on 06/25/17 at 11:47:18 I noticed today that the bike idles way higher when rainwater cools the engine, so that suggests it's indeed rich on idle. No more black smoke after polishing the needle valve seat and the motor responses very well to throttle. I hope I'll get the second carb tomorrow, going to rebuild that with a 52,5 pilot jet and see if it has a working idle mixture screw :D |
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Title: Re: Adjusting stock carb with modified engine Post by kojones on 06/28/17 at 04:45:37 New carb was in much better condition overall, diaphgrams like new. Excellent. Put in 52,5 and 165 and lifted the needle one slot, pilot jet is still rich, highest idle at screw 1/4 turns out. Main jet is a bit too small, few runs showed slight increase in power after WOT. Runs much better now, old carb had slightly torn diaphgram and also found out that my vacuum plug had developed a hole in it ;D Thanks to you all for your replies, seems like the correct size for the pilot jet is surprisingly small and surprisingly large for the main jet. |
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Title: Re: Adjusting stock carb with modified engine Post by savageguy1 on 06/28/17 at 16:49:56 0E29282830255C0 wrote:
or ( not to take away from lancer) just but a one off ebay and buy the parts you need to make it work I believe it is cheaper . the parts are list on the forum under ENGINE: MORE POWER. |
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Title: Re: Adjusting stock carb with modified engine Post by kojones on 06/29/17 at 05:00:37 6C7D72787D7B6E756C6F1C0 wrote:
or ( not to take away from lancer) just but a one off ebay and buy the parts you need to make it work I believe it is cheaper . the parts are list on the forum under ENGINE: MORE POWER.[/quote] This was my plan, the winter is long so lots of time to find correct parts and adjust the carb. I'm too cheap to buy a kit ;D. I put the old idle mixture screw in as it has different needle profile than the new one, 1-3/4 turns out resulted highest idle, so it's all fine now. Holiday starts tomorrow, so lots of testing in sight 8-) |
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Title: Re: Adjusting stock carb with modified engine Post by justin_o_guy2 on 06/29/17 at 06:05:36 What holiday is it? |
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Title: Re: Adjusting stock carb with modified engine Post by Dave on 06/29/17 at 06:21:22 Do they celebrate the 4th of July in Finland? :-? |
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