2001 gti rich/lean condition

[IANONTOP]

hello to all, i have a 2001 gti 720, with two issues im not quite sure how to gauge. This is a pretty gone through build light resto.

Issue #1 engine bogs at 0-1/4 throttle until clear then takes off. I know its a rich condition for two reasons, if i pull choke it dies. Also i remove spring for accel pump to disable and then the ski respnded normally from take off.

Issue #2 on the trailer out of the water at WOT i get backfires through carburetor. Not in the water, not at any rpm range with riding. Only with no resistance on prop.

Things that have been done
Compression check 135/140
Brand new mikuni carburetor w/accel pump
Stock settings L 1-1/4 h-0
New rv cover from sbt (522)
New rv valve sbt
Timed to 147 open 65 closed -/+ 1 degree.
Checked front cover for sheared key and re torqued.
Single fuel line with fuel filter to res on pickup. No selector or water seperator
Checked for fuel leaks or clogs all the way to the pick up

Suspicions
1 i didnt check was rv cover clearance. I figure aint going to get no better than new.
2 A thicker rv cover oring maybe pushing out the clearances a bit.
3 im using one of the stupid fuel filters with cardboard mesh.

TIA SORRY IF THIS WAS LONG.

 

[IANONTOP]

Anyone?

 

[mikidymac]

Did you install the correct jets, needle and seat and pop-off spring on the new carb?

I wouldn't use and aftermarket fuel filter?

Did you verify the new rotary valve was the correct degree?

Backfiring through the carb could be fuel related or rotary timing.

 

[IANONTOP]

Thanks for the reply!

I bought a new carb from wsm. Comes complete as a 1998 717 spec carb.
So 167.5 main and 70 pilot 1.5 seat pop-off was 37 psi i checked.

Yeah im going to put one of those free flow filters on.

Yes verified that the valve was 159 degree.

Okay im pretty ocd about the timing, and everything in the mag is stock from factory so i didnt remove the flywheel just the nut to check the woodruff key. i trust seadoo aligned the generating coil right.

Also i do you think my issue #1 has any connection or what do you think about that?

Thanks again really appreciate it

 

[mikidymac]

Too much rotary clearance typically causes very hard starting.

 

[IANONTOP]

Hey thanks for responding back! I meant issue#1 towards the top of my initial response.

Issue #1 engine bogs at 0-1/4 throttle until clear then takes off. I know its a rich condition for two reasons, if i pull choke it dies. Also i remove spring for accel pump to disable and then the ski responded normally all the way through the rpm range.

do you think this has any connection or what do you think about that?

 

[mikidymac]

Your jetting is wrong for a 2001 GTI

It should be:
167.5 main
75 pilot
2.0 needle and seat
115 gm spring
LS 1 turn out
HS closed

 

[IANONTOP]

For some reason my reply never went through.

I wanted to ask, why the jetting changed from 98-99?

Also if the change of jetting is necessary to the 98-99 change. what other engine accessories make the difference?

I’m basically saying that if the engines are exactly the same which most 720s are that I know of besides the 96 version which came with a dual carb intake and 97 version which came with no accel pump. I don’t understand why they would need to change the jetting? Is it the waterbox? Exhaust pipe?

TIA, just looking for more knowledge rather than just an answer. so please excuse my questions, and your help is greatly appreciated! Thank you

 

[JC-SUPERJET]

Probably to pass stricter Emissions Standards...

 

[mikidymac]

Not 100% sure but install the correct jetting and try it since you are having issues.

 

[IANONTOP]

Hello again hope everybody had a fun safe weekend, so I checked the engine. I see the year is 97 but the motor is silver. So I don’t know if that makes it a 98 considering I know 97 and down are white engines 98 and up are silver. I did salvage a motor from somebody else, and remove the original engine. I guess if I can figure out what exactly it is, I’ll put that exact jetting. I also have the old carb office engine. I will check. TIA

 

[IANONTOP]

I meant i salvage this motor from someone else