Low Speed Rich with High Speed Lean?

[Trhenning]

HI All,

Been doing a LOT of carb reading recently.

I have a 2001 GTI with a freshly rebuilt 717 Engine.

Broke Engine in, Adjusted the carbs for what I thought was well. Engine mount went, resulted in snapped bolt on exhaust and my carbs are poorly tuned. I fixed the manifold post, however, it's not running right. I can't tell if it is lean or rich when going to WOT. Help?

Symptoms:
Starts better without choke, but sometimes need to give it a quick squeeze on throttle initially.

Runs to top speed when Cold, Performance decreases as warm.

Loses Power on Turns.

Hitting WOT from 50% Will wait a second or two before acceleration kicks in.

Any Choke at Idle will kill the engine.

Some very mild backfiring possible, but not pronounced.

Any opinions?

Since it's a 717 engine, I don't have a tach.

Thanks!!!

 

[manolocross]

Stick with factory settings. High speed needle should be 0 turns out. And low speed should be 1 and 1/2 out from closed. Factory settings always run spot on IF everything is ok inside carb. Is it a single carb or dual carb setup. Slight backfiring can be a sign it's too lean. Check your spark plugs. If they are gray, it's too lean. They should be coffee colored. Idle should be 3k out of water 1.5 k in water. Very important! A lot of people set idle at 1k thinking it sounds right and then they put it in water and it drops to an unstable idle and dies! Get a cheapo tach reading device on fleabay for 10 bucks. Wire wraps around spark plug wires and reads rpm. I got one and it works great for setting idle. Good luck. Post results!

 

[Trhenning]

Thanks for the help! I think I am still a little lean, Gray on the tip now. Almost at the richest setting for the high speed adjuster. Jugs are 1.00 Overbore, Should I get bigger jets?

 

[1of500]

Not you should rebuild the carb again

 

[Trhenning]

Rebuilt the carb right before put the engine in. New needle and seat, too. Did not Change jets. Took it out, cleaned the passages, got back to basics and went Premix + oil injection 10 Gals fuel to 1 quart of Full Synthetic seadoo XPS2, carb is back in, no hesistation on lake so I am getting closer, but still getting gray plugs when running WOT.

 

[1983]

Gray plugs for me meant water ingress into cylinder. BUt this wasnt on a rebuilt engine.

After breakin you really need to put a fresh pair of new gapped NGK spark plugs in.

When engines are rebuilt there is metal dust and whatnot in it and it gets embedded on spark plug. Plus they are only $2.49 plus tax a pair.


Rob

 

[Trhenning]

I'll change to another fresh pair I have 8 extras sitting in the garage right now.

I know there was some water ingress when the manifold bolt snapped, but I think I would still be having problems if water were still there, rather than only having problems since warmed up.

Thanks for all the input thus far. Hoping I don't have to order new jets.

 

[Trhenning]

So I'm kinda frustrated. High speed adjustment screw the 1/4 turn out that is "Max" without taking the plastic cap off. Carb out, cleaned, rebuilt, and installed properly. Flame arrestor cleaned with carb cleaner, too. Running Pre Mix + Oil injection. 40:1 in the tank. Porcelain on plugs is white. Metal electrode is gray after 5 min WOT.

Runs great for 5 minutes when cold, then acts lean.

1.00 Overbore, Do I need to rejet to accommodate that?

Help please?

 

[1of500]

Way too much oil can cause a lean condition. Why are you running premix and injection?

 

[Trhenning]

Problem first surfaced when backing off premix after breaking in rebuilt engine.

 

[Roofer_tex]

Hi there I was just wandering if you ever figured out your problem I have the same ski and the same problem with power loss after 5-10 mins but it's not a rebuild motor

 

[benjilafouine]

On my 717, I set it to factory settings and used it for a while like that. Then I realized that it was running a little lean (because of the plugs) and gave the low speed screw 1/8 th of a turn and that made a complete difference. So in conclusion, you can set it a bit differently from factory but it will have to be very close.

Benji.

 

[Chester]

If everything on your engine is stock, set the mixture screws to factory settings and you will be good. If not, you have another problem.
Who did the engine rebuild? Was it pressure tested after the rebuild? Is your RV clearance within spec?

Chester