masterblaster
X-H2
I’m use to seeing some moderate temp differences in 62 t base motors I’ve had in past but current 964 is running much hotter on front cylinder in and out of water. Plugs read sim on both. Anyone experience this ?
Unequal cylinder temps on tpe 964
- Thread starter masterblaster
- Start date
waxhead
wannabe backflipper
- Location
- gold coast
What carbs and manifold
masterblaster
X-H2
Fs49 boyseen intake rrp pipe enlarged fittings for dual cooling. Equal length water lines in and out of billet head. Plug reads are similar. Msd tl new coils and plug wires Motor doesn’t run hot in water but front Cylin is always considerably hotter.
Normally I’d think partially blocked cooling lines or uneven size fittings lines ect. But temp diff on trailer running for 15 secs or so before heat soak is even more evident temp difference
My Dasa did that as well... think it was around 14 deg difference On mine @ the time, you could feel it with your hand as well... very odd.... frt cyl hotter than rear cyl.... no amount of water adjustment with different restricter for each cylinder changed it...
I noticed the rear carb, 49fs, dribbled at idle and on full throttle snap and elsewhere in rpm range. This dribbling was the cause, the extra dribbling fuel cooled the cylinder..
The front warmer cylinder was normal
It’s the cold cylinder In my case with the issue...
The best fix for the dribble in my case (wasn’t raising pop off or smaller seat or extra check valves)
It was changing the kidneys to a different model, the bore under the check valve flap “the clear check valve” is different, instead of straight thru bore this one makes a 90 deg turn and opens in a different location...
I’ll look and see if I can find the part number I used.. they were like $80 each
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masterblaster
X-H2
Thanks man. It’s funny I was just asking someone else about fs49s and how to stop the annoying rear carb dribble. Mine are doing same thing. He had moved the return jet from a 65 that I’m using to a 110 to lower fuel pressure.
I have Brand new doubled up check valves and new n&s That didn’t help much. These only do it when idle gets low and motor starts vibrating more. Now that idle is smoother it’s much less. That does make sense though. It’s off over 20 deg and easy to feel with hand. I forgot what laser temp was but it was a lot diff. Ran against dock with proks off. Fuel delivery at least looks very even through rpm range
I’m getting 1/4 inch vertical wear stripes in my front cylinder a bit worse than the rear cylinder also. Using 40:1 klotz. Bore clearance was double checked as well when rebuilt. I just don’t get how that much wear is happening on motor with less than 5 hours. Deff send me the source you got the part from. Worth a try.
masterblaster
X-H2
Who did you order from. Have a pic of them ?
Yamahapartshouse.com
Mine dribble was more noticeable at idle like you mentioned, I also noticed visually The sloppiness Of it as I opened the throttle as compared to front carb..
Here’s a pic, I don’t have a side pic handy.. noticed the hole is plugged in the photo and it’s relocated to the side and if my memory is correct, a higher position
Mine dribble was more noticeable at idle like you mentioned, I also noticed visually The sloppiness Of it as I opened the throttle as compared to front carb..
Here’s a pic, I don’t have a side pic handy.. noticed the hole is plugged in the photo and it’s relocated to the side and if my memory is correct, a higher position
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Traditional msd dual channel billet plates do NOT have the pickup triggers 180 apart. Depending how you are wired either the front or rear cylinder has advanced timing relative to the other. I recall I measured the difference and it was 2-3 degrees different. 2 seems to stick more than 3. The trick to get same was slot the msd pickup itself. 2-3 degrees advanced could produce more heat given everything else equal. A second reason could be the exhaust manifold you are using and it’s length of lines.
Quinc
Buy a Superjet
- Location
- California
Those kidneys are also in the gp1200 46i carbs. Might be cheaper to pick up a rack of carbs on ebay then buy the kidneys individual.
Quinc
Buy a Superjet
- Location
- California
Mikuni SBN fuel dribble
I have a 839cc big pin, ported, dry pipe, vforce Reeds, with dual sbn 46 carbs. I've been having a tough time with tunning the mid-range/transition. I noticed that it was loading up pretty bad so I rebuilt carbs with new needle and seats. On the trailer trying to tune low end I noticed that at...
www.x-h2o.com
With the dribbling in the rear carb, that rear cylinder is getting more fuel and oil than the front cylinder..... so it may be masking normal wear... as compared to the front cylinder
Quinc
Buy a Superjet
- Location
- California
I was told in 1997 or 1998 or around that time, when I complained to MSD, that it was so the rear cylinder (if wired properly) would be retarded from the front. Few people commented back in late 90’s/early 2000’s on rec.sport.jetki before forums. Very few people in the Freeride community ever commented (shows how many people actually tune their own stuff. I recall Chucky? Chiming in that this was a known design). I’m guessing most plates out there are still same. Haven’t used TL on a twin since 04’. Timed a ton for buddies and everyone was off front to back
you can actually see they are not 180 by starting at a plate!
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Quinc
Buy a Superjet
- Location
- California
Does the ATP TS2 have this issue as well?
Scribe/mark lines with a marker from one side to another at the tangent of the mounting holes and you will see how it’s off.
masterblaster
X-H2
Very interesting info. I’ve actually never timed both cylinders with tl, always just used front Cylin I don’t think msd would have done it if not helpful though. I’m sure their engineers know better than us diy tuners. Seems like more often than not when motors blow in one cylinder it’s the rear. Maybe a rear carb dribble isn’t the worst thing. My motor is still very responsive on throttle. 20 degrees just seems excessive