Out for this season..sigh...

Hi bob... the port and polish was only a "light" trail/ pump gas friendly job... I dont think it was an overly aggressive port job by mrviper...

your recomendations are alot larger then what he recomended...

please dont take offense in this bufalobob.... But mrviper does have alot of credability in his ability to make well tuned machines and yet have them safe for the type of riding we do... now as what he saw and a few others saw... it wasnt a burn down from lean conditions but from bad gas as like you said which is gotten inconsistently at different pumps... at 157 jetting... wouldnt I be flooding out my engine? and I am staying away from putting holes in my airbox... ive read it can be more of a problem then good... especially in the hands of a rookie tuner like myself...
 
your pistons are too lean for trail riding on pump gas. if you had more wash this thread would not exist. trail motors should be jetted for the worst posiible conditions. the only reason yamaha went back to the 2000 jetting on the 2002 srx was because of the DCS...it's a fail safe. it doesn't matter how much or little the porting is. once you increase h.p. you must add fuel. you're running a modified motor w/ stock jetting. it may work w/ good quality fresh high octane fuel....but not on pump gas. join dynotech research ( $20 yr. ). jim has articles on fuel quality & jetting. it's your motor. do what you like but if you continue to run stock jetting in a modified motor you will continue to have engine failure.
bob
 
Ride.Race.Live said:
Hi bob... the port and polish was only a "light" trail/ pump gas friendly job... I dont think it was an overly aggressive port job by mrviper...

your recomendations are alot larger then what he recomended...

please dont take offense in this bufalobob.... But mrviper does have alot of credability in his ability to make well tuned machines and yet have them safe for the type of riding we do... now as what he saw and a few others saw... it wasnt a burn down from lean conditions but from bad gas as like you said which is gotten inconsistently at different pumps... at 157 jetting... wouldnt I be flooding out my engine? and I am staying away from putting holes in my airbox... ive read it can be more of a problem then good... especially in the hands of a rookie tuner like myself...
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I'm running 152.5's across the board..stock 01 Srx burning alittle rich but could go out in -20 no problem...Honestly from what I've seen 155's for you my good man check the wash plugs and if you feel like you need less then giver...Jets are cheaper than pistons...Remember that
Someone can always give you a base line for jetting but it's up to you to dial it in...and the trick is to start out rich... If you check too lean..sometimes it's to late...Found that out this season...lol
But on a good note: Learned a valuable lesson...bahaha..Have to laugh it's sucked blowing up my baby...But she was up and running the next night...few beers, couple friends, lots of cut nuckles and greasy hands
 
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thanks for the info bob and 007redline... for me 157 seems abit too high... but I will go from a 155... and go from there... cause we dont see -20 very often.. mayb 1-3 weekends in the year? this year we saw only a few days of -20... then the rest was around 0 up to -15 tops at night... most of the time seeing -5 with a wind chill at -10

007redline... your telling me... this is my 2nd srx within 2 seasons of riding!... first one was a nightmare though... I didnt know enough about a srx to prevent anything from happening... was running 151's all across with a zillion holes in the airbox...(didnt check the airbox) I brought it to a mechs to have it checked head to toe and told him i want to get it back and just ride... well got it back and poped it after about 800km's into the season... 3 cylinders 1 head 3 pistons and crank bearings where toast... so parted it out... (alot more was funky on it then the airbox) too much to list lol....

But a point mrviper did throw out... if the sled feels dead and its muffled... its running overly rich... so basically you jet down fromthat point... just abit... but all i know is.. next season.. ill be testing and testing and testing some more...

and danm thats a pretty quick fix up on ur srx... lol... I dont have the funds to rebuild it that quick!... or else I would.... cmon lotto!!!! lol


Thanks for all your help so far guys! appreciate it!
 
This whole thread is sort of funny, but makes for a good read:) What I don't get is why the arguing about the jetting. The wash on the pistons looks fine, the guy that built the motor confirmed it looks fine, and confirmed a jetting baseline for the sled. Like always it's the responsibility of the owner to verify the jetting in the sled and make sure that it works for his/her riding style, temps, elevation, and fuel availability.

In my experience most of the guys that build motors for these things know what jetting their motor package wants. I've got a 700 redhead package from one builder out of Canada. I can ask him what I want for clutching and jetting for virtually any temp and elevation and he can tell me a baseline. He always ends the sentence with "that will get you close." That means it's up to me to dial it in. Since it's my wife's sled I choose to up the needles slightly from what was recommended, but otherwise it runs like a top. If it goes down will I ask his opinion? Sure will, but the bottom line is it's my sled, my motor, my responsibility.

I have one of Don's 780 motors in my srx. While discussing the motor I was given a starting place for jetting, fuel requirements, and it was quite clear that I had to warm it up properly. So I started out with slightly bigger mains and went to the lake for a little testing. Ended up that he knew what he was talking about and I'm running 152.5, needles at 4 with both over.

What I'm getting at is that the guys that build these things for a living usually know what their package wants/needs/etc... However it's still the owners job to verify those settings and adjust according to their needs. I've got 3 years on mine now. Had the heads off it over the summer and it was good to go. I make a point of warming it up good, buy my fuel from busy stations that sell good fuel, and always add an octane booster to take the edge off the fuel. This year I'm a torco accelerator fan. Stuff actually seems to work. Anyway, that's my thought on this deal. If you don't like Don's specs, then don't argue about it, just do your own thing. In the end it all boils down to the fact that it's your sled and it's up to you to keep it alive.
 
mrviper700 said:
Ride,race,live as you asked, I looked at your pics.
What I see from the pics is the correct wash marks on the domes, the pto cylinder with the biggest jet(150) looks the worst, too rich is why theres no carbon build up and still the front edge of piston eroded...,I will explain why shortly..

The center not so great...same 148.8,but it looks too rich as lack of carbon, and its all shiny not dry as being lean, it also shows the wash marks as needed.possible p/v problem/adjustment on this cylinder?.

The mag looks the best with a even amount of carbon on dome and wash marks at the rear,and side trans ports,this also runs the smaller 148.8 main jet so the part its "too lean" doesnt apply as suggested.

The second part of my observation looking at the exh edge of the pistons is eroded away,and the fact that they have carbon built up on the erosion and not silver from fresh detonation tells me it was done a while ago,not just since you were out when it was -20 below. Most likely from before you bought the sled, this can happen slowly if the detonation is only slight and happens a few times. This was likely from a tank or 2 of low octane fuel, it happens even to stock sleds.

You have a couple options to play it safe, the jetting specs I give for these are good to -10 degrees ,this is with premium fuel which is 93 octane,plenty rich and makes very good power. However, If you ride when its colder out or the quality of the gas where you use the most is not trusted,then you either can bump up the jetting SLIGHTLY, AND, add more octane. Adding more octane makes the sled richer with no carb adjustments!! I tell every single person in these days to always use octane booster, even on bone stock 2 stroke sleds!! Look at the amount of burndowns that have been on this site in the last 2 years even with bone stock sleds, so the suggestion the porting/wrong carb specs ruined it is not true.
If the carbs are set up to specs and spec fuel is used they are just as reliable as stock,its the fuel companys selling us short on quality and or lack of octane. A bottle of booster in the trunk is much,much cheaper then pistons. Sure,it wont make 87octane fuel into 93, but it will take the edge off premium if its a little short,and certainly not a big task to add. Use 1/2 bottle to a full tank, so you get 2 full tank fill ups to 1 bottle of booster. Again,its cheap insurance even on bone stock sleds, much cheaper then pistons!

Cold weather jetting:
42.5-45pilots (depending on how aggressive clutching is)
1.75 turns out on fuelscrews
needles 4th groove with both shims on top
152.5mains across, (more then likely you can use 150's all the way across because your richeng up the midrange circuit which overlaps with your mains.but if you have questionbale fuel or very cold a whisker richer main wont kill it off too bad power wise.)

airbox can have a couple extra holes in top but needs to retain the center baffle cone.

yes, this is same jetting I use for a std 780, it will be more then rich enough in your 700 and with octane booster as insurance youll be plenty rich, more jetting then this and it will be hollow sounding,flat and too rich resulting in noticeable loss of performance.
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That pretty well ends any confusion/questions on your jetting after you've finished your rebuild.[right from the horse's mouth]
Good to to see there are still people out there that stand behind + offer technical follow up to their work!!!
 
Do what mrviper sez's he knows his shit, he built the motor i would not take anyones elses opinon. I would "not" go to 157s way too rich, I was spot on with 158.8 with mrvipers porting vented to the airbox!! I went up to 160s to be safe.
I dont know why people insist on arguing becasue of this people like mrviper dont post here anymore and he is one of the reasons why this site is what it is.
 
not to hyjack the thread as there valuable information on here but how cold before meltdown stock jetting on a 2000 SRX 700 it is only use for snow drags and Ice drags. I don't use it that much on trails or riding around I just use it for testing & tuning and racing
 
I dont know why people insist on arguing becasue of this people like mrviper dont post here anymore and he is one of the reasons why this site is what it is
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Is that why he never made a follow-up to carb cleaning 101, cus I could really use it now :o|
 
Concept Carbon said:
Do what mrviper sez's he knows his shit, he built the motor i would not take anyones elses opinon. I would "not" go to 157s way too rich, I was spot on with 158.8 with mrvipers porting vented to the airbox!! I went up to 160s to be safe.
I dont know why people insist on arguing becasue of this people like mrviper dont post here anymore and he is one of the reasons why this site is what it is.
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yep just follow mr viper help and forgot about all other idea ...........
 
yea.... I was def keeping withing or just above mrvipers recomendations...

I will do some testing to see whats what....I want to see what the difference it does on a too rich curcuit like he described so that way I know that my sled isnt underperforming due to high jetting so my guess is starting at 155's and work my way down to as low as 150's If needed to... though I dont think ill go down that low if he recomended 152's for crapy fuel.. and colder temps

all sleds are different.. and ill do my testing based on what was recomended within close to mrvipers recomendations and go from there... if I have to.. ill post some pics and ask for more guidance from there...

..... Ive read my fair share of posts and every one... and i really mean every single person that has delt with mrviper ended up being a happy customer... Heck he even offered to do his piston mod for his "port set up" that i got at no cost as long as I can get the pistons to him... From his exact words...

"I will do it at no charge...as if its a engine of mine, I help people out no matter if its changed hands from the original purchser, no problem!"

Bendersrx (previous owner) told me to ask for mrvipers help and ensured me he would be the one to talk to for what i would need for tuning the engine to what I want it to do... and ill take his word on that for sure... actually modsrx... I think you go riding with bender once in a while eh?


It def is a shame that mrviper isnt around here anymore... he def was a great attribute to this site... and helped out countless people while he was around here... good thing we can still keep in touch with him if we need to though...for a moment like mine when i got some of his engine work done
 
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Ride.Race.Live said:
yea.... I was def keeping withing or just above mrvipers recomendations...

It def is a shame that mrviper isnt around here anymore... he def was a great attribute to this site... and helped out countless people while he was around here... good thing we can still keep in touch with him if we need to though...for a moment like mine when i got some of his engine work done
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Yep it's ashame.Therte use to be a guy on here just like mrViper when the site started he has done r and d testing for yamaha and his own dyno.He had his stocker srx's running nearly 130mph as i know mrviper has.He has bulidt a few of his own turbo's for guys.He know longer comes on here anymore because of the nay sayers and bashers.
 
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