SuzukiSavage.com - Big Bore Bobber Build

batman Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 3806 osceola new york Gender:	Re: Big Bore Bobber Build Reply #165 - 02/12/18 at 07:30:29 Dave ,we still don't know what he's running for jets. sigma idle jet ?what size is that? main jet? 145.160,170?
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Dave YaBB Moderator ModSquad Offline SuzukiSavage.com Rocks! Posts: 17893 Camp Springs, Kentucky Gender:	Re: Big Bore Bobber Build Reply #166 - 02/12/18 at 07:34:41 batman wrote on 02/12/18 at 07:30:29: Dave ,we still don't know what he's running for jets. sigma idle jet ?what size is that? main jet? 145.160,170? That is my point.....if you are getting mpg in the 30's, the bike is not running like it should.
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ohiomoto

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Re: Big Bore Bobber Build
Reply #167 - 02/12/18 at 07:54:28

Christof13T wrote on 02/10/18 at 13:46:45:

The video finally finished uploading...
This is what is was doing...

https://youtu.be/L_lxU2JgeyE

I pulled that cone filter off and put the pancake in its place at the end of the pvc pipe sticking out of that side of the elbow... made no other adjustment and tested it... some improvement but it still cut out around 35 in first under hard acceleration. at 45ish in 2nd.

came back to the house and turned the mix screw out anoher half turn...
tested it again and it now runs through all the gears under hard accel up into the 70's pretty easy...

WHAT GIVES!!???

---------------------------

I just watched the video and I'm not even sure why people were bringing up jetting. Jetting will not fix a mechanical problem. Fix the issue and then address the jetting.

I'm pretty sure the main issue, which you alluded to, was that the slide was not opening. When you open the throttle, it opens the butterfly at the mouth of the carb. This increases the vacuum that SHOULD be opening your slide which raises the needle and pulls more fuel and air. In the video, it sounds like you are just pulling a little more air into the engine and it is mostly running on the pilot circuit.

You probably fixed it right when you did the white spacer mod again. If it happens again, pull the air boot and watch the slide. It's probably not opening much at all. You should be able to raise it with a screwdriver (or your finger if you don't mind burns if it backfires).

If it doesn't open, make sure the diaphragm is seated correctly and not damaged. Also, make sure the slide isn't worn and dirty. Same with the inside of carb where the slide rides.

This happened to me. I didn't have the diaphragm seated properly. The bike wouldn't go past 20mph. Then later in the season, the slide started sticking at mid throttle periodically when the black coating on wore off and caked up in the body. A $125 slide and a good cleaning later, my bike ran fine.

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Re: Big Bore Bobber Build
Reply #168 - 02/12/18 at 14:50:57

Ohiomoto , a least part of the problem was "jetting" ,you think the slide wasn't lifting ,but he had not lifted the needle ,but dropped it.the slide was lifting but the needle wasn't letting enough fuel into the carb so he was running lean, and his sparkplug showed that. He should only be making one change at a time ,but he's changing slides ,jets ,air filters ,washers on the needle and fuel screw adjustments, all at once.That makes it impossible to know what's working or not working. You may be right about the slide sticking but we may not be able to tell until the jetting is at least in the ballpark.

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Christof13T

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Re: Big Bore Bobber Build
Reply #169 - 02/12/18 at 16:25:26

Well...
29.89mpg on today's trip of 67 miles from gas pump to gas pump.
65-70mph with cross and head winds. It starts to Peter out at 70 and flat out tops at 75.
Smaller pilot... bigger main, and another shim maybe?
Before anyone freaks out, I'm feathering and floating the throttle constantly dropping down to below 65 and then back up to 70... 72 for a minute or so, then slowly float it back down...

I am ordering a regular rebuild kit and a set of jets 2 freaking night!
Probably going to order a RYCA cone filter too.

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Re: Big Bore Bobber Build
Reply #170 - 02/12/18 at 17:24:12

Chris, bigger pilot maybe ,smaller main, You have to remember that the jets are cumulative , even at WOT your still getting fuel from pilot jet, needle jet ,and jet needle. If you keep your speed under 65mph( Which you seem able to make) you should not be using the main jet, unless the pilot is too small, if it is then your opening the throttle more (past 3/4) and starting to use the main ,which is much to large and killing your mileage . Your wind screen isn't helping, and the place to start is to get a decent muffler first,( if the stock one is drilled it could be half the problem) you can tune a carb to your exhaust ,but you can't do the opposite. 72 is your top speed because your going to WOT and running way to rich, If you were running to lean the bike would accelerate,( a slightly lean mix produces more hp) but it's not it's bogging .(rich) 170 jet is passing about 30% more fuel than a 150 jet .Are you running high octane fuel?

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Re: Big Bore Bobber Build
Reply #171 - 02/12/18 at 18:34:33

Premium pump gas. 93 octane.
I sent Lancer a pm about ordering a set of jets.
I don't trust what I see on ebay after the 6Sigma flop...
The pictres of the dyno research and dyno jet sets look like they come with a whole bunch of mains... but no pilots.. and like 4 needles... but in the description is states 1 set tailored to your application...

I'll go with the guy that deals with parts for these bikes specifically on the regular.

I get what your saying about why I should change which jets, and how backwards I was thinking. I'm starting to get it lol.

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batman Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 3806 osceola new york Gender:	Re: Big Bore Bobber Build Reply #172 - 02/12/18 at 18:59:26 I think Lancer puts together a good set at a good price . Glad your thinking about going that way.good luck!
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Re: Big Bore Bobber Build
Reply #173 - 02/12/18 at 19:29:26

I don't know what I am missing here but what is wrong with what Suzuki started out with?

The carb is set up by the EPA. You need to make it richer to run properly, however when you changed the air filter you started all over again. If the fuel system is set up stock. Go from there.

One thing I do know is that you only change one thing at a time. Evaluate what you did and then go from there.

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Re: Big Bore Bobber Build
Reply #174 - 02/13/18 at 06:19:40

Christof13T wrote on 02/12/18 at 16:25:26:

Well...
29.89mpg on today's trip of 67 miles from gas pump to gas pump...

Honeslty, you are so far out of the ballpark that should go back to stock or something close and start over. Keep in mind that the stock airbox breaths better than most pod filters. You may not need to go as rich as you think and right now, you are crazy rich.

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batman Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 3806 osceola new york Gender:	Re: Big Bore Bobber Build Reply #175 - 02/13/18 at 06:56:48 You might keep in mind that octane is a fuels resistance to burn ,which means that the flame front occurs much later ,and therefore not all the fuel may have time to ignite and gets pushed out with the exhaust gases. your mileage is running out your tailpipe.
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Dave

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Re: Big Bore Bobber Build
Reply #176 - 02/13/18 at 07:29:24

batman wrote on 02/13/18 at 06:56:48:

You might keep in mind that octane is a fuels resistance to burn ,which means that the flame front occurs much later ,and therefore not all the fuel may have time to ignite and gets pushed out with the exhaust gases. your mileage is running out your tailpipe.

I don't agree with that.....the Premium fuel required by the Wiseco piston does not burn so slow that it can't keep up with a slow turning single.

He may have such a rich mixture that some of it is going out the exhaust unburned - but it is not a result of the fuel octane. I have a Wiseco, I use Premium, and I regularly get mpg in the high 50's.

I am not a fan of small cone filters.....and I agree the stock air system likely works better and is easier to get jetted properly.

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batman Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 3806 osceola new york Gender:	Re: Big Bore Bobber Build Reply #177 - 02/13/18 at 09:31:00 Dave, you may be right ,but then if he's running as rich as we think how much O2 is there to allow complete combustion ? there may be a lot of raw fuel being exhausted for that reason. His fuel to air ratio may be pushing the 20:1 limit.
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Re: Big Bore Bobber Build
Reply #178 - 02/14/18 at 09:33:14

It acts significantly better with a 52.5 pilot and 145 main. It was holding 70mph at 2/3 throttle and didn't just bog down when I twisted into it at that speed... it wanted to giddy up. It still kind of flattened out at 75 ish on a downhill but I was in a pretty good headwind. I will run it like this for a tank or so and see what the numbers are looking like.

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verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28834 L.A. California Gender:	Re: Big Bore Bobber Build Reply #179 - 02/14/18 at 09:51:23 Hold it at WFO till you are at max speed. Then back it off a little and if it feels like it picks up a little, then go up a jet size.
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