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Message started by Tom Dooley on 10/09/11 at 18:20:12

Title: All Current TEV Discussion goes here
Post by Tom Dooley on 10/09/11 at 18:20:12

Warning: Please read the entire thread before trying anything. There are two TEV threads here in Tech Section, neither of which shows a consistent successful method for all mods/bikes -- your mods and jetting STRONGLY affect what the TEV adjustments actually do on your bike.

If you want to read the original locked thread on this topic, go here.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1268545171

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I just found an interesting thread on the below Suzuki Intruder/Volusia owners link:

http://www.intruderalert.com/cafe/index.cfm?page=topic&topicID=50668

This topic details and illustrates putting a 1/4" washer in the TEV housing to put slightly more pressure on the TEV diaphram. Article suggests the engine dying on decel and the decel backfiring are caused by the stock TEV enriching the fuel flow too much. The Suzuki Volusia twin has two TEVs and Volusia owners have been complaining of the same problem as our Savage owners. All of the people who made this mod reported it cured this engine dying problem. I inserted the washer on my Savage TEV today. This is an opposite mod compared to cutting the spring. I have made several test runs today and so far no further engine dying on decel. Will test this mod further.

Title: Re: Motor killing on decel - backfiring
Post by verslagen1 on 10/09/11 at 18:42:57

Great Mr dooley you've found another answer.
I'll add this to the TEV valve technical.

so here we have it,

Backfire... shorten the spring
Dieing at stop... lengthen it.

Title: Re: Motor killing on decel - backfiring TEV fix2
Post by Tom Dooley on 10/09/11 at 18:51:45

Actually both dying and backfiring on my bike has stopped. After completely going through the carb this little mod was simple to try and at the same time I converted to Allen head M4 screws. And it seems to work. Might just be the weather today. ;)

Title: Re: Motor killing on decel - backfiring TEV fix2
Post by spacepirates on 10/10/11 at 17:56:53

I've got the backfires real bad, and my bike stumbles on decel. You can hear it try and catch back up after you stop, kinda like catching its breath.

While I was working on my bike tonight I decided to take step one and "clean" (ha! i just shot carb cleaner around there...) the TEV to see if anything improves. I did notice gas sitting in there though. It was collected on the brass dish that holds the spring on the diaphragm. I'm guessing either that is normal or my TEV is too rich...

Title: Re: Motor killing on decel - backfiring TEV fix2
Post by SurfJunkie on 10/11/11 at 11:43:48

Just did this on my bike while on lunch at work.

I had a big tipped tight fitting phillips head screw driver. Screws came out with 0 issues/stripping.

The 1/4" washer i had would not fit on my TEV cover. I opted to put it in the metal cup of the diaphram ( where the spring sits anyway, essentially serving the same function as on the cap just without me needing to mod it. )

Took her for a test drive. VERY HAPPY ! I now only get 1 little pop every 15-20 throttle chops, rather then a solid kaboom every time i chop it.

Well worth the 5 seconds it took me to do.

I can also confirm i saw a little bit of fuel in the TEV diaphragm cap

Title: Re: Motor killing on decel - backfiring TEV fix2
Post by baker87 on 10/11/11 at 14:02:37

i talked to a buddy of mine... he said it is a combo of things, first being carb not metered and jetted properly... second the pilot air in the carb bowl needs to be upsized..... about 62.5.... and the pilot air in the slide diaphragm needs to be upsized.... no more backfire...

Title: Re: Motor killing on decel - backfiring TEV fix2
Post by arteacher on 10/11/11 at 16:01:39

Did this mod yesterday and took it out for a couple of hours today No backfires at all, just a few pops when backing off the throttle. Also the rpms do not take a dive anymore when letting off the throttle.
I am a happy camper. :) :) :)

Title: Re: Motor killing on decel - backfiring TEV fix2
Post by Tom Dooley on 10/11/11 at 18:36:44

The Volusia website states a 1/4" washer but I used a washer with a 5/16" ID and 11/16" OD and it fit perfect into the TEV housing. I had already converted to a .66" diaphragm spacer and backed out the idle air mixture 1/2" turn. I am running a stock exhaust and intake filter.

Title: Re: Motor killing on decel - backfiring TEV fix2
Post by SurfJunkie on 10/12/11 at 10:51:28

Ive discovered that my backfires are not gone completely. I think my issue is im just running rich. Ive got an 87 and it likely has the 155 main as stock. Im gonna pull the crappy airbox and put on a cone filter, then take her for a 15-20 min ride, then pull the plug and have a look. Oh the tuning fun begins.

Title: Re: Motor killing on decel - backfiring TEV fix2
Post by LANCER on 10/14/11 at 07:56:18

ah yes, tuning fun :)

Title: Re: Motor killing on decel - backfiring TEV fix2
Post by Tom Dooley on 10/20/11 at 17:55:20

I did some heavy riding today and was disappointed after the bike got warm and started to kill on decel. Just installed a tach and set the idle at 1250. Almost anytime I twisted the throttle a little when it came back to idle it would drop to 600-700 and almost die - sometimes actually dying. I removed the washer out of TEV housing and it did the same thing. I guess the next thing will be to try cutting the spring. I tried adjusting the idle mixture in both directions with no improvement. I am running at .062 spacer which I don't think even effects the idle. Stock exhaust and air filter.
Well, the good thing is, I needed a hobby and I sure have one now with this Mikuni ;)

Title: Re: Motor killing on decel - backfiring TEV fix2
Post by LANCER on 10/21/11 at 10:26:11

3E28393E2D22287D7578784C0 wrote:

Before cutting anything are you absolutely sure your carb is fully functional internally ?
The drastic drop in rpm when returning to idle and the resulting delay in rpm recovery or engine stop, could be the result of dirty or clogged passageways inside the carb body.
You turned the pilot screw in both directions without effect and that indicates a clogged pilot circuit. When working normally you will notice changes when adjusting the pilot screw.
This carb can be done in a day on your first teardown. It is helpful to have the small impact driver that Harbor Freight sell for about $8...used on the tiny screws in the bottom of the slide that hold the needle in place. Its good to have a bowl gasket on hand too.
There are some very small passageways that control fuel flow and if they are not clean & open the carb cannot work properly and respond to adjustment.
Once you know the carb is working properly then work on the mods if still needed.

Title: Re: Motor killing on decel - backfiring TEV fix2
Post by Tom Dooley on 10/21/11 at 19:27:38

Thanks Lancer for the info. I bought this bike just a couple of months ago and it had the problem then. Two weeks ago I dissembled the carb for cleaning. All jets were removed and cleaned including the float and needle. I did not find anything clogged. It appeared this was the first time the carb was opened up. The carb body was dipped and all jets cleaned with a small copper wire and inspected. The TEV was clean also. The only thing the first owner had done was installed 3 washers (totaling .072") replacing the original white washer (.10"). I replaced the .072" spacing with a #4 nylon washer (.062"). At the time I replaced the phillips heads with allen heads. I have always used a 3/8" impact but I bought the Harbor Freight 1/4" for this project and it worked great except for 1 hard headed phillips which I had to use vicegrips on. It runs great except for the dying on decel. I can kick up the idle to 1500 and that helps but it should be able to idle at 1100-1200. If you have any further ideas I would surely appreciate. Thanks

Title: Re: Motor killing on decel - backfiring TEV fix2
Post by LANCER on 10/22/11 at 12:57:21

I find the brass jets themselves are less likely to clog before the passageways in the carb body itself. The root cause of a majority of difficulties encountered in trying to tune a carb comes from cloged passageways.
The little brass tube that sticks down from the carb body into the float bowl about 1.5" has a very tiny hole that runs from the tip up into the carb body. Just below the tip of that tube is also a tiny hole on each side. Thats part of the pilot circuit and needs to be clear for proper function.
Another item is the needle jet. With the main jet removed the NJ can be gently tapped out through the top. It has quite a few tiny holes on the shaft that are usually clogged on an older bike/high miles.
Sudco sells a carb tool that is a small metal case with about a dozen tiny wires of the sizes needed to work on carb bodies. They work better than any wire you can rustle up and the set is cheap. The price is worth one clean & rebuild of a carb. This way you know without question that everything is clear and flowing fuel and/or air.

Just some thoughts.
Good tuning. ;)

Title: Re: Motor killing on decel - backfiring TEV fix2
Post by Tom Dooley on 10/22/11 at 18:05:22

Thanks for the carb info. When I went through the carb last week I did not take the needle jet out. I only removed the main jet and pilot and checked them. I remember blowing out the the tube that goes down in the float bowl. I am going to pull the carb again and make sure I clean the needle jet. When I first looked in I could not figure how to push the NJ out and hoped the carb cleaner soaking would do the job. I know something is not right in the idle circuit or TEV circuit for it to be dying when I "blip" the throttle. I will order the Sudco cleaner tool kit. I don't hesitate to acquire the right tools. Thanks again.

Title: Re: All Current TEV Discussion goes here
Post by misterbbq on 11/06/12 at 12:11:18

i took the cover off to clean out behind the diaphram while i had some other parts of the carb off for rejetting, cleaning. one bad part about doing maintenance with the carb on the bike....if a part falls off it lands in some part of the engine that is apparently a black hole.

the tev spring seems to have wedged itself somewhere i think i can hear when i roll the bike back and forth but can't seem to see, feel or find. FRICK. i managed to rejet the carb with no issues and then i lose a frickin spring.

anybody know of any special hiding places to look? again, i THINK i hear it rubbing something when i roll the bike to and fro, but cannot see anything. have a new one on order, but don't figure it's a good idea to let stuff rubbing on other stuff down there.

Title: Re: All Current TEV Discussion goes here
Post by Gyrobob on 11/06/12 at 12:25:49

5C5842455443535340310 wrote:

A trick I often use when working above places that can act as a black hole for small parts is to cover up those places with towels. I also prefer working on a large piece of terry cloth as well because little pieces don't roll as far on cloth like that.

I can really relate to what you are saying. I have probably spent several hundred hours of my life looking for tiny lock washers, pins, springs, o-rings, etc.

Title: Re: All Current TEV Discussion goes here
Post by Blinky on 11/06/12 at 12:45:17

IDK if this it it, but there is a opening behind the starter on that side of the bike. You might want to run a wand magnet around in there to see if you can come out with the spring. I have lost two speedometer cable washers and a jelly bean down there.

good hunting

Title: Re: All Current TEV Discussion goes here
Post by misterbbq on 11/06/12 at 16:41:47

a jelly bean? lol. that would be my luck.

thanks for the tip....going to go see if i can find that little cubby hole.

Title: Re: All Current TEV Discussion goes here
Post by misterbbq on 11/06/12 at 17:40:09

turns out it did fall into the 'jellybean zone'. between the starter and the pulley eventually wedging itself behind the pulley. i didn't see where it went initially because i was trying to catch the cover as it sprung off with the last screw.

so....as with most of posts, let this be a cautionary tail to you guys doing anything with your tev.....BE CAREFUL with the spring loaded cover and the spring loaded spring as well!

new one should be here friday.