SRX Jetting and Piston Wash Questions w/ Pics!

T

Theicor

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Well, here goes, looking for some good insight on what I have going on here. This is a 98 SRX engine with about 3500 miles on it, the last 500 of them in the mountains w/ a mod sled. The jetting is at 150 straight across Needles at 3rd clip, no washers, stock SRX pipes, w/ Bender can. Stock airbox and ATACC for altitude compensation, my base Jetting is for 1000' altitude and about 0 degrees F. I am looking at the wash I have now, and I want to say that it is right on the line where I might be tending to the lean edge, but not too bad. Here is where things get interesting, I am adding some Hauck handbuilt pipes, and Mega Power Heads. I am trying figure out how much I may have to change the jetting for this combination. My guess would be that I would go up two sizes to a 152.5 across since I feel I am slightly lean anyway, I have ceiling some room to work with, and I would maybe put a washer inder the needles at the third clip. What do you guys think of what I have here. The pistons are arranged from left to right - PTO, Center, Mag with the exhaust side of the pistons facing the right.

BTW - You may notice the mag side has some material melted off the crown of the piston on the exhaust side of the piston. Comments would be appreciated on this condition. My guess is this: being the wash is pretty decent, and the fact that I had a bad spring on that pipe which was replaced halfway through the season last year, the melted edge is caused by having a loose pipe on that cylinder. :o|

Well guys, have at 'er, please keep comments constructive... ;)!

Thanks!
 

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Since you're at 3500 miles, I'd change the pistons and rings, since you already have them out. I'd run 155 mains across the board and put the clip in the middle with a washer underneath. It may be on the rich side but it's easier to change the jetting than a piston. The pipes will want more fuel. The mag side piston will eventually fail with the crown gone on the exhaust side. Why chance anything going wrong when you're on the snow. Just my thoughts.
 
Thanks for the info, yeah, I forgot to mention that I am freshening the engine, I wouldn't put that garbage back together. You think I could really get away with going up that much in the mains, wow, but I think we agree that I do have a lot of room to spare on the fatter side. I like to hear your suggestion on the needle clip too, that tells me I am thinking in the right direction. Thanks for the comments, I am just thinking out loud here... :rocks:
 
What you don't know is how much fuel the new pipes and heads will need. Don't assume that going to 152.5 will take care of the new items. I'd run the new rings in on the fat jetting then check the wash to see what that looks like then do whatever the wash tells you. You can also check the wash in the midrange along with the top end. Better safe than sorry.
 
I'm in sort of the same boat right now and have run my newly ported 98 motor 1 day so far. I am running on the fat side for now as well. My question is why are you not staggering the jetting. I think I have mine staggered correctly according to the manual (mag side is fattest?? dealer told me pto side but I think that is for 2001 and newer srx). The jets I took out were straight accross wondering where I need to got with this? Thanks for any help
 
That is correct, for the 1998 the mag side is fatter. I went with a straight jetting mainly because of the Bender can and the fact that I am running this engine under a mesh hood. This basically gives me the effect of a really good cold air kit and keeps critical jetting factors of the engine such as the PTO and the underhood exhaust temps more consistent across the engine. It seems to work from what I can tell by the wash and the EGT's, they seem pretty even across the board. You mention you are on the fat side, what are you running for jetting?

BTW: I have a stock 1998 SRX 700 for ditch bangin' and I run the stock jetting setup in that...
 
I too have a mesh hood with a bender can. I am running 147.5's and 148.8 with an ATACC and a base elevation of 3500'. Exhaust temps maxed out at 1195 last time out but i haven't really pinned it for very long yet.
 
That sounds pretty good, I know mine would run up to about 1250 if I really got on 'er. Yours sounds pretty close. ;)!
 
You can't base your jetting from that wash unless you pulled the motor apart after a full throttle clean shutoff run. At anyrate your left piston is right on the border lean, the other 2 look pretty close to the way I run mine. SRXM5 sounds like your getting closer. Have you checked your wash? Are the exhaust temps still rising or does it seem like they are staying at 1195?..........SRXtreme
 
I've only been out the one day about 50 kms on the motor. I took it easy but it was hard to do. I did a couple of small climbs and and walked all over my buddies 800 poo and I didn't even have it nutted.The suspension changes are awesome.Now I need to figure out how to replay some pulls on the digatron.I guess maybe when it warms up i'll hit the lake and check the wash. So far the plugs are a really nice cardboard brown. Talk at you soon
 
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