High-rev problem

[MikeC]

I was wondering if someone has any experience with a "racing engine" problem on a first gen Venture.

 

Mine will start running at a higher RPM (about 1500) after a short time in city traffic. It doesn't seem to be stuck cables. The throttle retracts all the way and I can bring it under control at a stop by holding the brake and feathering the clutch in first gear - 1 or 2 times brings it back down to normal. The real problem is any longer diving at highway speeds. After an hour at highway speed the engine will run at 3k when I stop. The clutch method above works but as soon as I let it go, the engine starts climbing to about 3k. It doesn't jump up to 3k but I sure wouldn't call it a creep either.

 

Anyone have any ideas?

 

MikeC

[GeorgeS]

I have heard similiar stories. Never happened to me.

 

I think I would start by lubricating the Throttle Linkage assembly's, between the 4 carb throttle plates. Also might be a sticking Throttle Plate shaft.

 

Check your Throttle Pull Cable, at the Left Forward Carb. Make sure there is some amount of Slack in the cable with closed throttle. ( 1/16th to 1/8th inch of slack )

 

Also, check the Exposed part of the Pull Cable for any sign of fraying---

 

Also, back out the Master Idle Adjust Screw, untill Its NOT makeing contact, now you should have some slack in the cable. Check your idle speed. It should be running about 600 rpm, then bring the screw back up close to 8 to 900 rpm, and see what you have. ( Re evaluate the situation )

 

Most likley you will need to do the Re-Sync Proceedure on the Throttle Linkage Assembly.

[Thom]

it has happed to me ,kinked choke cable allso when i start gaining a 150 rpms when the motor gets hot i know i need to syc my carbs.

Thom

[Marcarl]

Had that problem this spring,,, drove me nuts,,,that's why I am what I am. Did everything you could think of, lub the linkage, checked the cables, worked on the cruise and then gave up, because I had sync'd the carbs and that just wouldn't be it,,,wellllllllll,,,it was. Got right back to square one on the carbs. Set #2 so that it closed,,,completely. Then did the rest of the carbs in order,,,,,,,,,,,,guess what,,,,,,,,,runs beautifully,, no more problems.

Need more info on that, just ask.

[MikeC]

Thanks, George. I'll try that tomorrow after work.

 

I recently had the cables apart for another reason and checked for fraying, particularly on #3. None there. I lubed all the cables and linkages at that time. But it was a quick lube - I didn't spend a lot of time there.

[MikeC]

That's what I get for answering the phone while writing a post! Thanks, guys! I'll try synching tomorrow also.

[BradT]

If all the cables are good, then it is a dirty carbs, clean it with a Carbtune. Fixed it for me.

 

Brad

[hipshot]

If all the cables are good, then it is a dirty carbs, clean it with a Carbtune. Fixed it for me.

 

Brad

BRAD, and Mike!

while i firmly believe in the "cleaning" properties of "SEA-FOAM",

i will tell you both here and now.

Sea Foam , is NOT a magic "cure all".

my '86 has been doing this for over two years.

no amount of sea foam, bowl draining, diaphragm changing, linkage adjustment, CARB TUNING,cable lubing, etc, has helped.

i have NO vacuum leaks. carbs ARE synced, needles are set correctly, the beast still idles fast, and GAINS rpm.s as the engine warms up.

it WILL NOT idle at less than 1400 rpm.s

just jt

[Dano]

it WILL NOT idle at less than 1400 rpm.s

just jt

 

Just that much quicker to the red line!

[BradT]

JT I am not saying that either. Sounds like you been fighting a problem for a while without a fix. Sorry to hear.

 

On my 81 Seca I had an issue that when the engine warmed up, it would rev up when the clutch was pulled in. I am not talking 1400 rpm, it would climb to 3000-3500, a real pain when you trying to Gear down, bike would want to speed up.

 

You had to brake to a stop with the clutch in, then hold the brake while letting the clutch out, to slow the engine down. When the engine was at normal idle, (1000) you could pull in the cutch and it would be fine untill the next stop.

 

Seafoam solved this issue for me, and I believe it helps on certain specific problems . I do not use it on a regular basis like some, I use a half can in 5 gallons, two maybe three times a year.

 

Brad

[Snaggletooth]

Hey Mike.

 

When I first bought my '84 I had all kinds of problems with the engine revs running up. Mine turned out to be a carb problem and I ended up rebuilding them and the problem went away.

 

Seems the carbs were overloading with fuel and it was loading up like you were pulling the throttle open. Floats and needles fixed it for me.

 

A vacumn leak can cause a similar situation. A rubber line heats up and a crack will spread and the off she goes. As soon as it cools down it goes away.

[friesman]

My 85 ran well ,and idled great until i paid some guy to chaNGe my valve cover gaskets. While he was in there he said might as well synch the carbs,,,,well I dont think this guy had a sniff of an idea on what to do , because right after that my mileage dropped and when it warms up the idle goes to around 2500 rpm.

I figure its just one more thing to have a look at when the engine is outta the bike this winter and Old buddy ole pal Rocket is fixing my trans.

 

Brian