01-11-2011, 06:32 PM #1
- Join Date
- Jun 2010
HX with Westcoast head, 44's, twin pipes, etc...JETTING???
Hey all, just got my 1996 HX running and in the water. It has a Westcoast head (160psi compression), dual redtop 44's (I believe their 44's but dont know how to verify), FPP twin pipes (not sure what they are from, but they have been modified), MSD box, R&D intake manifold, etc.
I rebuilt the carbs and observed 20psi pop-off pressure on both carbs, and jetting was 95/135 and 107.5/135 with low speed adjustment at 2 & 1/4 turns out and high speed at 1/8 turn out.
The ski runs like garbage. It will idle in the water for about 30 seconds and then die, and requires using the primer to get it started again. It runs great midrange, but bogs out and dies if you attempt anything over half throttle. Sometimes I feel the high jets kick in for a second or two before the bog out. The bogging is worse with the flame arrestors on.
I attempted to open the high speed adjustments to 1 full turn out and it seemed to come alive a little better top end for a second or two before bogging out again.
Im not sure if it isnt getting enough fuel to the carbs, or if the high/low speed adjustments are off, or if it might need a rejetting?
Any suggestions are greatly appreciated, thanks!
01-11-2011, 07:07 PM #2
- Join Date
- Apr 2006
- panama city beach 'fl
well as far as I know no 720 hx ever had twin pipes,jetting sound like to fat -can ya take some pix of motor might be 800 or 951
also you might try installing fuel pressure gauge and see if starving at speed
but pix would be nice
01-11-2011, 07:38 PM #3
01-12-2011, 09:15 AM #4
I'm not familiar with Red-Top's or a Dual Pipe set-up on the 717 but my previous FFP'd HX w/ Mikuni 44's had the following Jetting.
This was a fully Ported (Cases and Juggs) engine--
Main=120 MAG 125 PTO
01-13-2011, 05:59 AM #5
- Join Date
- Jun 2010
Thanks for the replies guys. I forgot to mention that the needle and seats are 2.5's. Also, another friend looked at the carbs and thinks they may be 38's, but we dont know either way and dont know how to verify the size? Also, Im not sure why the previous owner would have put these jets in the carbs to begin with? I plan on getting the jetting FPP recommends and going from there.
01-13-2011, 06:52 AM #6
you can get a cheap micrometer from auto zone to check the throat size on the carbs....good luck with the FPP rep. If the same B$#@! works there answering the phones you wont get much. all she will do is tell you to read the directions if you have them or not and she is extremely snotty about it.
01-13-2011, 12:36 PM #7
01-13-2011, 12:47 PM #8
44's look *nothing" like 38's---For starters, the Throttle Body has both High Speed and Low Speed Adjusters on the same side.
The 44 also has both Throttle Rods linked together with a Coupler instead of the 38's Linkage Bar. Just Google Mikuni SBN44mm and SBN38mm,, plenty of Pix out there.....
2.5 sounds way too big for a 717 engine
01-13-2011, 01:13 PM #9
01-13-2011, 05:42 PM #10
Post a pic of the twin pipes.
Only twins I ever saw in the 1990's for 650/720's was made by PSI.
I had a set..
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