Author Topic: I got the Vroom Vroom (Read 2604 times)

Ericcb750 · « **on:** March 02, 2014, 01:17:31 PM »

Hey Guys, Well I've finally got the bike running, and it stays running now! I broke down the carbs this week, and Cleaned them like crazy, pulled everything and cleaned with carb cleaner and compressed air (jets, floats, needle, even slides). When I was looking at the floats I noticed that they seemed a bit low, like the idle jets wouldn't be submerged (not sucking up any gas). So I adjusted them and hooked them back up and I got The Vroom....awww yeah. ha-ha. Good feeling considering it's my first complete re-build including the engine. But now that I fixed one problem, I have another....story of life. When it's idling now and I blip the throttle it jumps up to 2500rpm-3000rpm and sits for a few seconds, then it will come back down. Does anyone know why this may be? If anyone has any advice or has dealt with similar issues that would be a huge help. it's a 1978 - PD 42 carbs, 35 idle jet, 110 main, Needle (non adjustable) with a tiny shim. Idle screw is set at 1.5 turns out. Thanks Guys

Powderman · « **Reply #1 on:** March 02, 2014, 01:20:23 PM »

I was thinking maybe you bought a Mazda.

martin99 · « **Reply #2 on:** March 02, 2014, 02:49:39 PM »

Why the shim? Have you got pods?

Check for air leaks around the carb rubbers, when you know that's all good synch the carbs. That's what I did to fix the hanging throttle on mine.

Ericcb750 · « **Reply #3 on:** March 02, 2014, 03:55:25 PM »

No I have the stock airbox, stock 4-4 pipes I've read that these came lean in the midrange and that it helped to raise the needle, since it's non-adjustable I put a very small washer underneath. I'll check on the boots also to make sure they're all tight but they're in really good shape still plyable.

Vinhead1957 · « **Reply #4 on:** March 02, 2014, 04:08:42 PM »

My vote is the advancer springs are worn out behind your point breakers plate

faux fiddy · « **Reply #5 on:** March 02, 2014, 04:10:21 PM »

Check cable routing and lubricate them well. WD may not be the best but you can blast it through the housing and it will help.

harisuluv · « **Reply #6 on:** March 02, 2014, 04:58:23 PM »

That is very typical of a rich mixture that can be fixed with the airscrews. Don't know where you're at but try turning them in 1/4 turn at a time and see if that helps.

Ericcb750 · « **Reply #7 on:** March 03, 2014, 03:25:22 AM »

Hey guys, thank you all for your help. I did put brand new push and pull cables on because the old ones were a bit slow. I checked the advance cam behind the points plates and everything seems to be nice and tight but moves freely. If this can be caused by a rich mixture I can try turning in the fuel screws on each carb a little. Are there Air screws on these PD Keyhole carbs? I thought there was just the Large idle screw between the 3&4 carbs ? I could be wrong though. I'll keep trying to figure this out. I appreciate you all taking the time to help me out. Take it easy. Right now I have the fuel screws 1.5 turns out.

Stoli · « **Reply #8 on:** March 03, 2014, 05:37:27 AM »

They called them airscrews on the earlier carbs but harisuluv was referring to the fuel screws on your PDs. You will tend to find the terms used interchangeably on this forum. If you have them each out 1.5 turns, try closing them in small (1/8 - 1/4 turn) increments to see if that helps.

Ericcb750 · « **Reply #9 on:** March 03, 2014, 07:18:05 AM »

Oh alright that makes sense, I'll try making adjustments to the fuel screws and see if that helps. I will also check the timing with the strobe light, Now that I have it able to run and stay running I can hook that up. I will keep trying to figure out what this may be. If the timing was off could it cause the engine to run like this? If this is typical of a Rich Mixture as Hairsuluv stated , then I will try and turn the fuel screws in a little at a time and see if that helps. Thanks guys.

Ericcb750 · « **Reply #10 on:** March 05, 2014, 08:49:57 AM »

Hey Guys, thanks all for the advice. I'm going to have some time after work to check out the bike. I'll check the Carb boots and I will also try adjusting the fuel screw. Anyone else have similar problems that they have run into? I'm think the weather up here will be warming up soon and I hope I'll be able to take the bike out. I'm a rookie to this stuff so any help Is appreciated. Take it easy guys.

Duanob · « **Reply #11 on:** March 05, 2014, 10:09:35 AM »

I didn't see anywhere that you did a vacuum sync after going through and reinstalling the carbs. That could be your problem right there.

thelowmax · « **Reply #12 on:** March 05, 2014, 10:45:05 AM »

I always thought that would be a good name for a club for racers… The VoomV Room.

Ericcb750 · « **Reply #13 on:** March 05, 2014, 11:54:14 AM »

Oh that makes sense. Is there any other way to do it without a set of those 4 gauges ? I don't have a set but if there is no other way It will be an investment I'll have to make. I'm keeping this bike so It would be a good thing to have I guess. Thanks Duanob

strynboen · « **Reply #14 on:** March 05, 2014, 12:04:09 PM »

the only vay to get a sohc running perfekt,,is to vaccum cyncro..it takes all rattel aut of the engine and give a smooth drive..its like a new engine after a cyncro..you can run for 2-3 years after this.(.if nothing are thanged)..so it must be done..or you dont get all fun aut of the bike...

Ericcb750 · « **Reply #15 on:** March 05, 2014, 01:32:41 PM »

Alright sounds good guys. Thanks . I'll look into getting one , what is the best type to get? The mercury type of the one with the four gauges ?? Or is this something different that I'm thinking of?

Duanob · « **Reply #16 on:** March 05, 2014, 02:02:58 PM »

It's a matter of opinion but I have the 4 vac gauges. It was cheap ~$50 and easy to use.

Bru-tom · « **Reply #17 on:** March 05, 2014, 02:12:00 PM »

i dont know why more people don't make their own manometers, its really so easy to make and its cheap as ever??

strynboen · « **Reply #18 on:** March 06, 2014, 07:25:24 AM »

i use the gauge type..they are easy to hook up..and no flouid spill...to vash up...but vhy bay a set..are there not somone have a set neer you..

syncro film 1

i did not adjust the small"drossel "schrevs..if they are aktivatet the resultav vil be more presise...the needels vill be more stabile....

a ekstra fuel tank..and a strong air blower is needet...it can take 10-15 minuts to get it right..

Bru-tom · « **Reply #19 on:** March 06, 2014, 07:31:28 AM »

i put vacuum restrictors i made into the tubes, they fluctuate a tiny bit at each stroke. hardly enough to suck in the oil from the tubes. A decent bench synch is always handy to have done before

Ericcb750 · « **Reply #20 on:** March 10, 2014, 02:22:22 PM »

Hey Guys , thanks for the help. I got it running pretty well this weekend. I found that the no. 2,3,4 exhaust pipes had a bit of play in them where they attach to the heads. When I was running the bike, I stuck my hand down in front of the pipes and I felt puffs of air. Once I fixed those and got them all tightened up, It sounded better. I'm still having a bit of an issue with the hanging rpms. But I'm trying to see if one of my buddies has a set of the vac gauges that I could borrow before I buy a set. I also turned the fuel screws in a bit, to 1.25 turns each and that seemed to help with the idle too. I'm wondering is there anything else that might cause the idle to be a little jumpy?

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Author Topic: ** I got the Vroom Vroom ** (Read 2604 times)

Author Topic: I got the Vroom Vroom (Read 2604 times)