Hard to start when warmed up

[cutlass]

Working on a 2002 GTI LE with the 717 engine, single carb. It runs really good and the compression is 135ish on both cylinders (a little low?).
When you shut it off after riding, its hard to restart. After some research, I found 2 common concerns for this: Rotary valve clearance and leaky needle/seat.
So I measured the rotary valve clearance at .025" or more. I stopped sticking feeler gauges in at that point because it was way out of spec (.010" to .014" is spec). Took the cover off and it was worn quite a bit and had a sharp lip/edge around the outside diameter where the valve worn into it. So I ordered a SBT reman'd cover and installed it. Measured the clearance at around .019"...still out of spec but way tighter.
Disassembled, cleaned, and checked pop-off for the carb. All good there, N/S holds pressure and pops-off normally.

Back together for a water test and this thing still runs great(maybe better, got 2 mph faster) but is still hard to start when warmed up. Before it was nearly impossible, now it starts okish when holding the throttle wide open. I can live with that maybe but I'd like to fix it.

So do I need to tighten up the rotary valve clearance more or does it need a top end to bump up the compression or does it need something else?

 

[Dr Honda]

I'd say... you are fighting a double issue. Still too much clearance on the RV, and compression at the edge of acceptable.

Do a top-end, and it will help. When you put the new cover on... did you replace the valve?

 

[cutlass]

No I didn't replace the valve. Thought about it, but didn't. Its a steel valve, correct? I didn't expect it would have much thickness wear on it to give me a clearance problem but maybe it does.
I should be getting closer to 150psi with a fresh top end, correct?

 

[- BiRkS_]

Yes 150 should be expected, but I would be more leaning towards leaky Needle and seat (still) if it requires full throttle to start, it is obviously getting too much fuel. Compression really doesn't play a part, because when compression gets too low, normally you need more mixture/running it on choke. Leave the top end until fall, as long as you put quality oil in it, you won't be in trouble.

 

[cutlass]

Yeah now I kinda wish I put a NS in it when i had it apart, but with the rotary valve clearance issue and the good pop-off tests, I thought I nailed it down to the RV clearance. Next time I ride it, I'll try to get a better feel for if it seems rich or not.
Next question is, how does the RV clearance affect starting? I assume it doesn't seal and bleds off compression making it hard to start. So maybe i can run a warmed up compression test at the dock, after a good long ride? Will that tell me something?

 

[Jimnut]

What was the pop off when you measured it?

 

[masdbo]

Cutlass, I have a 2001 GTI with the 717, single carb.... I am having same problem.... I would ask, If you try to restart right away does it start well? If you wait a minute or so does it take alot of cranking and have to hold throttle open? That's my issue and it is fuel bleeding past the carb needle valve I think. Try turning your fuel about 15 secs before shutting off and see if it's still hard to start.

 

[cutlass]

What was the pop off when you measured it?

It was 33 psi, but I've noticed my gauge is a little low (Its low on my GP1200 and GSX Limited carbs). But its in the general "ball park" and those ski's run perfect. I think its time for a new gauge.

Cutlass, I have a 2001 GTI with the 717, single carb.... I am having same problem.... I would ask, If you try to restart right away does it start well? If you wait a minute or so does it take alot of cranking and have to hold throttle open? That's my issue and it is fuel bleeding past the carb needle valve I think. Try turning your fuel about 15 secs before shutting off and see if it's still hard to start.

Yes, I actually did try that now that mention it and it did start ok without giving it throttle. That does kinda point towards it flooding a bit from a leaky NS. I'll take it out and try it again and try you're idea of shutting the fuel valve off 15 seconds before shutting off the engine. That should kinda empty the fuel lines and carbs and prevent the flooding. Thanks for the idea!

 

[masdbo]

No problem, and related to this issue be advised, a couple times on me, I tried to start before taking it out and found that the engine was hydro locked! Pulled the plugs and straight gas shot out! This can be really bad for the engine, and it might make you think you have a weak battery. Cranking while hydro locked can blow seals and damage major engine parts. Also make sure the fuel tank vent is clear, it can build up pressure and cause that.

 

[cutlass]

Geez! that would suck. Yeah, I haven't had that happen yet because I usually leave the gas valve off when its not on the water. But I'll keep that in the back of mind in case I run into it. I'll check the vent...maybe tonite if my GP1200 project goes smoothly and I have some extra time.

 

[cutlass]

Check valve and pressure relief valve check out ok...well I think they do. The check valve definitely is ok, thats easy to test. The pressure relief valve does hold pressure and then release pressure if I keep pumping. But its hard to measure 1.5 psi like the manual says. So I'm gonna say its ok since it holds and releases pressure.
Its been too cold and rainy for a water test, but I should be able to this Saturday.

 

[cutlass]

No water test. The guy that owns the ski wants it back today.
But he said he'll bring it back over. So here's my plan of attack:
Skip the diagnostics and replace the needle/seat and the rotary valve. I suspect it might be a little worn and causing my extra RV clearance.
Question, can I cheat on the rotary valve replacement by marking where it came off and just sliding the new one on in the same place?