Trying t0 figure out compression numnbers here???

bluemonster1

bluemonster1

LIFE MEMBER ONLY ONCE!!!
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Howden ,Manitoba,Canada
after putting on some 50 miles yesturday,let sled cool off for a few minutes and took compression of cylinders.Sled doesn't want to pull at wot very good.Got to 95 mph only and wot rpm's at about 82--8300 again.Even after I lightened the tip slightly.The numbers I got was 116 psi across.
Then this am in the garage at about 45 F took another test without warming up motor and got 123 mag...122 center and 121 PTO..Thought I had a compression issue but it is showing consist throughout the range.
Yet my SRX ain't performing well on top end.

Basically stock set up.

8dn-20's with 4.5g inner and 3.8g outer(drilled 4.5 rivet) with y-w-y spring.Have 47 stock helix at 80 with red spring.The belt is still within specc at ..33.75 mm..clutches cleaned and belt scrubbed.Why the hell can't I pull the wot rpm's.I can try to drill outer rivet to get it to 3.6 again and see.

Track is loose and rotates on stand so no resistance there.Could the belt be an issue.Why would rpm's stay low on top.If it does climb close to 8400 at 1 point,at a long haul it is only at 8200 rpm wot.Super snappy at mid range..pulls your arms.At launch I am raising skies and even at 40 mph it will do same..stumped here.
Clutches parts..bushings,rollers and weight all good and bushings also.It fells like something is holding me back from behind like an anchor..weird.PV's all good and adjusted to......................starts great also,better then last season even....stumped here
 

I adjusted them last weekend and reved up on the stand and the servo motor rotates after 6000 rpm's..will check again I guess but don't see an issue here......man oh man!!!

I'll warm up the motor outside,put on stand again and watch the servo and then take another compression of cyl. warm again.....
 
Weird Doug, you were showing a higher reading today?? Maybe that tester is kinda screwy, who knows though. Not riding today???
 
no biggie..I feel tired again..it is close to 0 out to so SRX won't perform like I want it to.The main thing I am getting is consistency across.On your v-max I checked this am and now you are at 110 across
 
don't laugh there mod.That friggin v-max is quick off the line.You can raise the skis a foot on a good launch.I think it has a 1 inch track on it to..I am surprised at it's acceleration from a dead stop.
 
Is it suppose to be higher when cold?? Already priced out a top end kit for under 250 genuine yamaha parts. Cost you about 475 for the srx(pistons,rings,circlips,wristpin bearings, piston pins) cheapest I could find from the states of course. Also watching some pipes on ebay, if I can get em for cheap enough I will save them for next year and do it all at once as i will need to jet up with the pipes.
 
bluemonster1 said:
don't laugh there mod.That friggin v-max is quick off the line.You can raise the skis a foot on a good launch.I think it has a 1 inch track on it to..I am surprised at it's acceleration from a dead stop.
Click to expand...


Plus shes leaned out pretty good and sits pretty low but yeah she moves!!
 
I am melting the snow and ice off the v-max..man does that sled ever accumulate of lot of it..taking forever to melt.I want to put your back end up on the hoist and look over the skid good.I know that your seat is ready to come off,it shakes and can be lifted on the back.Felt under the tunnel and the 2 nuts and washers are on the last threads of the bolts..need to tighten them.I will try and find that other grease fitting on the back of skid to and check everything once lifted up high enough.
 
found my more expensive comp. tester in the shed.Complete different numbers..but constant...

mag side--128 psi
center--127 psi
pto--132 psi

now what..engine seems to be ok with no psi low numbers.Checked servo and it is turning normally and all valve cables are good and valves adjusted.Just won't pull on top..like I mentioned seemed like someone was holding me back..like pulling a skier behind me.Brakes off,track spins easily..but does it ever ballon at 7-8000 rpm on the stand..maybe tighten it up more.
What could be causing me not to open it up..like get the rpm's at wot easily to 8500.....something electrical??? You think a new belt could help??Even if old one in spec and has lots of life left.... :o|
 
ya a little happier feeling inside.Now I got to work on clutches and or PV's.Will swap clutch from SXR.But am using my spare clutch now and since it weas reb uilt summer 08 it hardly was used at all..still stumped..maybe the belt thingie
 
yes bevel down .....got all week to check things again but getting tired of taking things apart anymore..wish it was summer so I could be cutting grass instead already.Sledding ain't like it used to be..fun!!!
 
if I can't get the SRX up to parr soon..it is going into the Red River here when the flood starts up again...got my sandbags already and can't wait to put up my flood wall.... :o| :o| :o|
 
I mean reeds is probably the one thing you never checked yet Doug. Probably still original and I bet there not working 100% which could cause you to lose some crispness and top rpm power.
 
It's worth a try. It's tell if there messed unless there really bad
If you tAke them off and hold em up to the light there should be
no light coming through and they should be flush. But if you can't
see light they could still be messed . Just on break picking up a free signal on my phone. Lol
 
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