squish problem?

[chrisdoc0608]

I hate to keep asking questions regarding jetting, but ive been trying to get my new motor properly jetted and tuned for a while. im at the point now where it hits very hard every were but off of 1/4 throttle, when i hold it then go wot it makes a distinct gargling or burping sound then clears up and goes. from a dead stop to wot it does a little better than from 1/4 to wot. could someone please verify if this sound is cause by a rich condition? What should i do to try and eliminate it. i have tried multiple pop off pressures with new n&s and springs, currently i am at 25psi and it has been the best thus far. i have a 140h and 120l. i began at a 150h and 130l and dropped to 145h 125l, each time i dropped performance improved.

i really dont have a reliable piston wash to determine that i am spot on bc the motor had a lean piston wash when i bought it. it has become a little better looking since i began tuning, but it still looks lean.

thanks


EDIT* Read post #16

 

[#ZERO]

Maybe it's not a fuel mixture problem but more to do with ignition advance curve.

What kind of CDI are you running and where's your static timing set?

 

[chrisdoc0608]

static timing at 2* advance, running an msd and lightened stock 61x flywheel


btw it is a ported 62t case, ported 61x cylinder, single 46mm. last ride was with a stock head at 147psi (raised ports dropped #'s a little) , now have a girdled at 170psi

 

[#ZERO]

Increasing the blowdown time by raising the exhaust ports could have something to do with the sputtering at low speed too.

Try adjusting your water pipe screws first and increase the exhaust back pressure in the pipe.

 

[chrisdoc0608]

im running a coffman sizzler, no b-pipe... i know, i know im cheap lol. i do have a jetworks restircter in line to the stinger. would allowing more water in the chamber increase the back pressure?

in addition to that is it possible that one of my circuits in the carb is too rich or lean, like my low jet? the noise it makes is very distinct and changes the tone of the exhaust

 

[#ZERO]

Yep, try adjusting your flow control valve and maybe play around with the timing.

Usually gargling, burping or sputtering on the low end is not fuel related; if it was the carb you would have a dead spot in certain throttle positions or even surging.

 

[chrisdoc0608]

the gargling problem is now gone, its quite odd. I put on a girdled head with around 165-170 psi, and now i cant get a steady idle without it cutting off in the water. i also was able to turn the low speed all the way in while trying to get max rpms on the trailer and it was still climbing (didnt do this before the girdled head). I think i may need to go down a size on the low speed jet. In addition the ski ran so crappy with the previous settings that i had to turn my high speed out an additional 1.5 turns (2.25 total) performance continued to get better as i turned the high speed out but i ran out of day light.... so before i go and re jet AGAIN, what would moving up back to a 145 equal in terms of turns out. i thought i read somewhere that an increase in jets is equal to 2 turns, so would that mean that .25 out with a 145 = 2.25 out with a 140?

 

[chrisdoc0608]

anybody

 

[Mike W]

When I ran a single 46 my jetting was 125p, 130m 95gm spring with a 2.3n/s (25psi popoff) and it ran pretty well. However, I had stock porting, 62T cases with a Riva manifold but yours should be close.

 

[Mark44]

Try starting over and using a tachometer to set the carbs you can't go wrong.

Mark44

 

[chrisdoc0608]

When I ran a single 46 my jetting was 125p, 130m 95gm spring with a 2.3n/s (25psi popoff) and it ran pretty well. However, I had stock porting, 62T cases with a Riva manifold but yours should be close.

there is no way that i can run a 130, it was WAY lean with this 140 (right now 2.25 turns out and still may not be spot on)

i have a 2.0ns and 95g spring and i have 25psi... how did you get that with a 2.3

Try starting over and using a tachometer to set the carbs you can't go wrong.

Mark44

i have a tach mounted next to the primer, but it doesnt register fast enough to give an accurate reading and it seems to be off as if it reads double. ex my idle reads 2400.... before i put the girdled head on i hit 9k which i know this ski cant be doing.

If i do get a tach that reads changes fast enough, how in the hell do you read it while maintaining a full throttle?



any ideas why these things are happening after installing a girdled head? would a bump in compression just amplify the effects of a lean motor and thats why i didnt experience them with the stock head? im just confused and frustrated at this point

 

[Mike W]

there is no way that i can run a 130, it was WAY lean with this 140 (right now 2.25 turns out and still may not be spot on)

i have a 2.0ns and 95g spring and i have 25psi... how did you get that with a 2.3



i have a tach mounted next to the primer, but it doesnt register fast enough to give an accurate reading and it seems to be off as if it reads double. ex my idle reads 2400.... before i put the girdled head on i hit 9k which i know this ski cant be doing.

If i do get a tach that reads changes fast enough, how in the hell do you read it while maintaining a full throttle?



any ideas why these things are happening after installing a girdled head? would a bump in compression just amplify the effects of a lean motor and thats why i didnt experience them with the stock head? im just confused and frustrated at this point

My mistake, I meant 20 psi. I did try a 2.0 which gave me the 25psi.

 

[Mark44]

o

You may want to do a search this has been discussed in detail on how to set carbs properly with a tachometer. I think there is also something in the FAQ section from Randy at Watcon on how to adjust carbs. :fing02:

Mark44

there is no way that i can run a 130, it was WAY lean with this 140 (right now 2.25 turns out and still may not be spot on)

i have a 2.0ns and 95g spring and i have 25psi... how did you get that with a 2.3




i have a tach mounted next to the primer, but it doesnt register fast enough to give an accurate reading and it seems to be off as if it reads double. ex my idle reads 2400.... before i put the girdled head on i hit 9k which i know this ski cant be doing.

If i do get a tach that reads changes fast enough, how in the hell do you read it while maintaining a full throttle?



any ideas why these things are happening after installing a girdled head? would a bump in compression just amplify the effects of a lean motor and thats why i didnt experience them with the stock head? im just confused and frustrated at this point

 

[Mark44]

Here you go found this.
http://www.x-h2o.com/threads/39846

Mark44

 

[chrisdoc0608]

thanks mark, but i have read that article a couple of times before. my question is if i do get a tach that reads changes fast enough, how in the hell do you read it while maintaining a full throttle... the way i have it now it is squirly as hell at full throttle if im trying to bend and check the rpms on the tach... maybe im missing something



and in that article did you notice that he says to go no further than 50 kilometers while testing starts.... thats close to 31 miles

 

[chrisdoc0608]

I think i have definately found the problem to my odd occurrences. I just went to check the squish on the girdled head and noticed that at tdc the piston is low in relation to the dome... the squish i measured was .080
am i correct in assuming this would cause all of my sudden weird problems and the massive amount of turns i had to go out on the high speed?

I swapped out the domes with the large squish with a set of 31cc domes. and compression was 195 and squish .078 so i believe that i would encounter the same problems either way.

what can fix this?

 

[chrisdoc0608]

...:shrug:

 

[750SX]

are you using two pieces of solder and making sure that it is against the cylinder wall?

 

[chrisdoc0608]

two pieces at once? no i am using thin solder that i had to fold onto itself and twist into a thick enough piece, it still flattens out, and now that i have a digital caliper the measurements are not a guess. I bent the solder and could feel it hit the cylinder wall, i will attempt it a few more times and see if there is any change in my measurements. I think im going to sell this head on ebay and purchase one of the heads that trls63 makes... they look nice and the girdle kit is sweet plus it uses ada domes so i dont have to look for parts for this off name head.

do you think that the large squish is responsible for my sudden problems upon switching heads?