Low Rpms when the temp is warmer

saskattakman

saskattakman

New member
Joined
Dec 17, 2005
Messages
243
Age
42
Location
Sask Canada
runnin my 98 msrx....the sled is jetted to -40 C so i know im running rich when the temps are -5C....the problem is im short about 200 rpms....when the temp is about -15 to -40 it rips pulls the right rpms at 8500 (ported engine)....is the rpm loss caused by the engine being rich or is it caused by the snow being heavy and wet and loading the engine down more??? my sec is set at 80 wrap now should i go to 90 and try it or am i gonna have to rejet?? getting ready for the 1000' drags tomorrow so well see how it does
 
Yep its just really fat at warm temps. My viper did it real bad after I piped it, so I put on a vari flow. Maxdlx
 
Oh ya... like maxdlx said it's way fat at -5C when jetted for -40C. If your secondary is a 80 then switching it to 90 wrap will help some. When it's -10 out my stock SRX runs great, when it's 0 I lose about 200 rpm aswell and if I add 10 degrees to the secondary preload it normally gets me back to where I need to be. Apparently I'm not supposed to gain 200 rpms from adding 10 degrees twist... but for some reason I do when it gets warmer.

Works for me so try it and see if it works for you. You should really jet down though if you want all available HP for 1000' racing.
 
did a couple plug chops to see what its runnin like....plugs look a nice chocolate brown and the wash is about a pinkie nail where the boost ports are....still thinking about this.....could the warmer temps make less power as the colder the air you have coming in the more power it makes even if your jetted to temp....tried the wrap at 90 and still not quite there....how much wrap can i go on the green spring??
 
well out at the drags this past weekend.....beat most of the 2 stroke stuff polaris 800 and 900's AC 700 and 800's ....couldnt quite get the 4 strokes....was my secondary at 90 holding me back some??....also how reliable are the variflows??? previous owner had one but removed it cuz of a burndown...still pulling 8300 rpms..should i rejet or do some clutch work??
 
I would say that your secondary is holding you back some (60 wrap for racing is ideal)and some tuning in the primary is necessarily to get close to target rpm, but your jetting is what is effecting your clutches. So look to your jetting first. The problem is you are going to have to screw with stuff in different temps and snow conditions...so if you want to be as fast as possible, you are going to be tuning all the time. If you want to be close, leave it like it is...Pick the temps and snow conditions that you ride in most of the time, unless you like to tune....My 2 cents!!!!
 
ok so if im jetted at 150 150 and 152.5 to -40C and wash and plugs are good at that temp....what should i change to for around -10 to +5 or so???....so i shouldn't touch my clutches?? running with 2.4 grams in tip of 8bu's with www primary and green sec...been through the powervalves and none are pulled and all are adjsuted right...
 
Do you have a manual? I use the jetting chart from my service manual and then work my way from there, factoring that yamaha jets real rich from the factory. I would jet for temps and would leave the clutches alone till the jetting is dial in!!!!!! Most likely you will not have to do anything to the clutches when you get the jetting correct. I can't give you specifics because I have a srx6.
 
ya i have a manual....the jetting will be off from that tho cause my engine is ported....what spring is harder then a www??? looking for something easier them pulling carbs everytime...if it was as simple as a spring change that woudld be much easier....or i might put on a variflow
 
The thing is, if you are running pig rich you are loosing out on hp....you can clutch for the lost power but you are leaving ponies behind!!
 
good idea....so if im jetted at 150 150 152.5 for -40C what should my jetting be for -5C??? or what are the variflows like???
 
y-w-y but ask turk what he think about it ... i know ported engine seem more affected with different temperature
 
You must log in or register to reply here.


Back
Top