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Discussion Starter #1
well i got the "chopper" out of the shop again. she was running a shade rich, but i thought it wouldn't hurt the new top end to get a little extra lube and cooling. i took off to make a 6 mile trip to my buddies shop and she was loading up pretty bad. i got on it hard, got throught he gears, only to see blue lights. luckily, the cop was cool, he could tell my bike was pretty sick, and he just let me go. i got the shop, went down one step on the mains and did a quick around the block ride. it seemed better. i started it up again, and the idle was 1500 rpm too high, and wouldn't come down. also, the float vent was pouring gas out. it was midnight, i have to be up at 5:30 in the morning, so i just rode it home. the cop was waiting for me in the same spot, but this time i wasnt doing 70 in a 45. i got home, shut the gas off to get the bowls dry enough for me to store it in the house and though that screwed my plug check, i still pulled them anyway...still rich. i'm going to go down one more step i think, and do another check for air leaks with the carb cleaner spray technique. if i don't have an air leak, im going to take the floats out and make sure my needle seats are good. also...im going to do some test runs this weekend. does that sound pretty good to you guys or might i still be missing something? i find it funny that everybody told me an RD with chambers and pods would need a 220-240 main on it, yet i am still rich at 140. anyway, shower some wisdom down upon me.
 

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someone here will have a jetting base line im guessing.

jc
 

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while you are tortuting my chopper

here is just a basic something to keep in mind....

if your oil mixture is heavy........ the resulting fuel mixture will be lean....... plenty of lube but still a lean mixture to be lit off in the warmer/hotter chambers

if your oil mixture is light....... the resulting fuel mixture will be rich......... lube lacking but cooler chambers and rich running


and this is true regardless if your jetting is spot on or otherwise.......

just something that is often overlooked with two strokes but good to keep your head wrapped around

before you start jetting.... make sure you are running the best two stroke mix you can buy and make sure it's mixed right

and once you jet, mix consistently with the good stuff and if running good stuff.... you can use oil/fuel mix to very slightly tweak or dial in "jetting" for variables due to weather and such........

keep notes and pay attention to both the ambient temp and barometer
 

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Discussion Starter #4
hack, im using the stock injector and oil pump set up. i dont think that the mix is coming into play. i think that i had an airleak and bad crank seals before, which was giving me bad plug readings AND false idle settings. now that i have all new seals in the bottom end and im pretty sure no air leaks (going to test that out this afternoon) i think i can get a good baseline. my cousin and i talked about it, and we think that the duel stage pods i used are actually more restrictive than the stock box...meaning that its not getting as much air as we thought it was. i dont have the stock box for it, so im going to tune it for the pods, and then maybe over the winter switch to a k&n + y-pipe set up. i think a day or so of tuning and i can have this thing spot on. all the other systems on the bike seem to be a go. ive jetted a BUNCH of race bikes in my day, but nothing "old" to where i was having to make sure needle seats are clean and all that stuff. thanks for all the ideas, im going to go torture your chopper some more this weekend. i might even make it to a bike show if i get it tuned in early!!!
 

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Tyler:

I'm sort of in the same position. I too have pods on my RD400. When I switched to expansion chambers, I had to start adjusting the jetting. I started with 220 mains and 27.5 pilots. I have the needle in the second from the bottom position. Right now, power delivery is smooth and linear up to around 7K RPMs, then it tapers for about 500RPMs before shooting off like a rocket.

I installed new plugs, and will see what they look like tonight. But do keep us posted as to your progress. I'm new to 2-strokes and jetting carbs in general, so i need to learn all I can.

--Thanks, Chris
 

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I would disconnect it and mix my own..... this way you don't have to think the oil mixture may not be an issue

you will know and never have to lose one minute's pleasure worrying about that old injector pump, or any of it's cables/bits/etc, failing

some of them failed when they were new
 

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Discussion Starter #7
nah man, i trust that injector pump. i had the same set up on my RT100 dirt bike and it never failed me. i'm keeping the injector, it is just too easy, and i don't have to carry oil with me either. see chris, you are at 220 jets...where everybody says i should be...im at 140 and running rich? i have some carb work to do. i'm going to fool with it tomorrow afternoon and let you guys know what i come up with
 

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Tyler,
I'll preface all of this with I don't know shit about 2 strokes. I've owed a weed wacker a chain saw and managed to not blow them up.

Anyway, slow down, listen to Hacka. Don't confuse gas/oil mixture issues with jetting issues. And counterintuitively it's probably why you holed a piston the first time.

Call Hack. Listen to your step father.

My $0.02

Cheers,
Leo
 

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call me?

he knows he's in trouble and too skeert to do that phone thing much less come see me

my guess is he's already heard my abilities to hypnotize are not limited strictly to personal meetings


Leo, we've talked on the phone........ would you mind quacking like a cow?

reminds me I need to intrude into your day soon, last time seemed to be good for sales ;)
 

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Discussion Starter #10
oh no no, im not discounting hack at all, he's my step-step pappy. But i have ruled out oil as being my problem. i holed the pistons the first time because of a perfect storm of issues. (1) clogged petcock (2) bad crank seals (3) air leak. i think now i have dirt or maybe a spot of rust (from the tank before i creamed it) messing up the float needle seat, and that is causing my overflow issues. after that, it is just going to be test and tune. i'll have it fixed up this afternoon im sure. my buddy is on the way over, and if we each work on 1 side, we can get this done pretty quickly. he's bringing his FZ over too, so he can follow me on my runs and see whats up. and hack, i'll be over your way just as soon as i get stuff settled down here. i mean, im a professional race mechanic now (meaning, i clean bikes and fill tanks and put air in the tires) and i have to travel this time of year!!
 

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well you could at least let everyone know what it cost to retain you
 

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Discussion Starter #12
right now, my services are just to take care of my expenses....but back to the chopper. ok, i started it today, its running on 1 cylinder. fuel, shooting out the exhaust. i have compression, and a weak spark on the right side. so i go to the shop, buy new spark plug caps (after testing that it was the weak link) and buy the premium (EV's, not ES) plugs. put those on, fire it up, my spark is fine, but still no fire on the right cylinder. we took the carbs apart, and the slide on the left side wasn't seated right, so that took care of my idle problem, but fixed little else. we checked the coils, they were both good, so then i said heck with it, and we both rode it. the bike would pick up on the right cylinder under a load, but then go back out...i mean, it was just shooting fuel into the motor like crazy. so i figured out that i wasn't going to be riding for the day, and i put it up, spark plugs out of the heads to let it air dry a bit. i came back to it tonight after running some errands, and pinched the fuel line shut to the right side....it ran. i then ran it with the fuel off. just as the bowl was about to empty, it would run fine. here is my synopsis...when i changed the jet the other night, i some how screwed the float up. its too dark to mess with it now, but im going to adjust the float level tomorrow and see if that is the culprit. right now, it is just like pouring gas into the spark plug hole! so now this is going to cost me another 2 quarts of gear oil, because im sure my cases are full of fuel now from running it about 3-4 miles on 1 cylinder. if you guys have any other things to check, let me know!!
 

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quote:Originally posted by 2smokeTyler

nah man, i trust that injector pump. i had the same set up on my RT100 dirt bike and it never failed me. i'm keeping the injector, it is just too easy, and i don't have to carry oil with me either. see chris, you are at 220 jets...where everybody says i should be...im at 140 and running rich? i have some carb work to do. i'm going to fool with it tomorrow afternoon and let you guys know what i come up with
Have you checked out and asked your question on usa2strokers?
There are many people on that site that race,tune,build/re-build RD/LC/RZs. http://www.usa2strokers.com/forum/default.asp

Don't discount your float levels/needles at all.
They are critical especially on a two stroke.

Keep in mind also that the stock Yamaha oil injection runs very,very rich(50:1?) in the HIGHER rpms and much,much leaner(200:1?) in the lower rpms.

With modern oils that run HALF(40/60:1) or more as lean now(compared to 20/30:1)your bike's oil injection can't and doesn't know the difference! It will still pump in the same amount as it always did no matter how lean the oils CAN be mixed with the fuel.

When you don't pre-mix your depending on a VARIABLE air/fuel and OIL ratio. That adds one more dimension/factor(headache!)into the equation. One that is harder to predict/tune due to the oil pumps variable/constantly changing(throttle position/rpm dependent)design.

You may be able to adjust it? Some injection units you can and some you may not be able to. Don't know which is the case with the RDs.

Did you change/adjust anything on the injection system when modified the bike with jetting/pipe,pods etc.? Remember your injection unit was built to maintain a STOCK RD and may need to be tweaked for a modified one.

Here's links to the 2strokers site/answers:
FAQ page:
http://www.usa2strokers.com/forum/forum_posts.asp?TID=15191&PN=1

Oil Pump Adjustment for RZ & YPVS RD, RD250&350 (AC), and RD400 (AC):
http://home.mchsi.com/~xen-uno/RZ-YPVS-RD350-OilPumpAdjust.p df
http://home.mchsi.com/~xen-uno/AC-RD250-350-OilPumpAdjust.pd f
http://home.mchsi.com/~xen-uno/AC-RD400-OilPumpAdjust.pdf

http://usa2strokers.com/forum/search.asp?KW=oil+pump&SM=1&SI=TC&FM=0&OB=1
http://usa2strokers.com/forum/search.asp?KW=Jetting&SM=1&SI=TC&FM=0&OB=1
http://usa2strokers.com/forum/search.asp?KW=tuning&SM=1&SI=TC&FM=0&OB=1
http://usa2strokers.com/forum/search.asp?KW=premix&SM=1&SI=TC&FM=0&OB=1
 

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that which has been bolded is where many two strokers become confused and because more oil (richer?) in the mix means LEANER to the engine

one must really have their noggin wrapped around the concept before attempting to articulate it or begin actual tuning

from what I am reading.... it would appear you agree that mixing your own is ideal

quote:Originally posted by coolatula

quote:Originally posted by 2smokeTyler

nah man, i trust that injector pump. i had the same set up on my RT100 dirt bike and it never failed me. i'm keeping the injector, it is just too easy, and i don't have to carry oil with me either. see chris, you are at 220 jets...where everybody says i should be...im at 140 and running rich? i have some carb work to do. i'm going to fool with it tomorrow afternoon and let you guys know what i come up with
Have you checked out and asked your question on usa2strokers?
There are many people on that site that race,tune,build/re-build RD/LC/RZs. http://www.usa2strokers.com/forum/default.asp

Don't discount your float levels/needles at all.
They are critical especially on a two stroke.

Keep in mind also that the stock Yamaha oil injection runs very,very rich in the HIGHER rpms and much,much richer in the lower rpms.

With modern oils that run HALF(40/60:1) or more as lean now(compared to 20/30:1)your bike's oil injection can't and doesn't know the difference! It will still pump in the same amount as it always did no matter how lean the oils CAN be mixed with the fuel.

When you don't pre-mix your depending on a VARIABLE air/fuel and OIL ratio. That adds one more dimension/factor(headache!)into the equation. One that is harder to predict/tune due to the oil pumps variable/constantly changing(throttle position/rpm dependent)design.

You may be able to adjust it? Some injection units you can and some you may not be able to. Don't know which is the case with the RDs.

Did you change/adjust anything on the injection system when modified the bike with jetting/pipe,pods etc.? Remember your injection unit was built to maintain a STOCK RD and may need to be tweaked for a modified one.

Here's links to the 2strokers site/answers:
FAQ page:
http://www.usa2strokers.com/forum/forum_posts.asp?TID=15191&PN=1

Oil Pump Adjustment for RZ & YPVS RD, RD250&350 (AC), and RD400 (AC):
http://home.mchsi.com/~xen-uno/RZ-YPVS-RD350-OilPumpAdjust.p df
http://home.mchsi.com/~xen-uno/AC-RD250-350-OilPumpAdjust.pd f
http://home.mchsi.com/~xen-uno/AC-RD400-OilPumpAdjust.pdf

http://usa2strokers.com/forum/search.asp?KW=oil+pump&SM=1&SI=TC&FM=0&OB=1
http://usa2strokers.com/forum/search.asp?KW=Jetting&SM=1&SI=TC&FM=0&OB=1
http://usa2strokers.com/forum/search.asp?KW=tuning&SM=1&SI=TC&FM=0&OB=1
http://usa2strokers.com/forum/search.asp?KW=premix&SM=1&SI=TC&FM=0&OB=1
 

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and I do also agree that today's modern two stroke oils require far less oil in the mix to provide even better lubrication to engine's internals than the best oils which were available when the RD was made
 

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Discussion Starter #17
im not premixing my bike. so lets just rule that out. i am not going to carry oil with me, and im not going to just dump oil in my tank and hope that pumping gas in it mixes it enough. i like the injection system, seems pretty bullet proof. i ran the same type of injection system on my dirt bike for 3 years and that was before i knew what maintenance was...and i never had a problem. i have clear oil lines on the bike to make sure i am still pumping oil at all times. USA2strokers is a waste of time. their FAQ's are good, but their forum is shit. i've been through the FAQ's. there is me, and 2 actual experience mechanics helping me with the bike and after all the tests and runs and what not, the only thing we can figure is float levels. im going to mess with it today and see what i come up with. i really wish you guys were here to see what it is doing and to actually ride the thing! that would make this much easier! LOL! will keep you guys posted. thanks for the help
 

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quote:Originally posted by 2smokeTyler

im not premixing my bike. so lets just rule that out.

sissy


i am not going to carry oil with me, and im not going to just dump oil in my tank and hope that pumping gas in it mixes it enough.

carry it in your purse

i like the injection system, seems pretty bullet proof. i ran the same type of injection system on my dirt bike for 3 years and that was before i knew what maintenance was...and i never had a problem. i have clear oil lines on the bike to make sure i am still pumping oil at all times. USA2strokers is a waste of time. their FAQ's are good, but their forum is shit. i've been through the FAQ's. there is me, and 2 actual experience mechanics helping me with the bike and after all the tests and runs and what not, the only thing we can figure is float levels.

bleh bleh bleh ... yeah but if they had any sense they'd tell you to premix and if you wouldn't listen they'd kick you in the junk


im going to mess with it today and see what i come up with. i really wish you guys were here to see what it is doing and to actually ride the thing! that would make this much easier! LOL! will keep you guys posted. thanks for the help


translation.... because this is Hack's bike I'm going to blow it up again
 

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Tyler,
The oil injection system is not your problem. Do not listen to these faithless heathens that are afraid to trust modern doodads like oil injector pumps (even if Yamaha has successfully using this system since 1964.) Your problem is too much fuel getting to one cylinder. That was proven when you restricted the fuel flow and it improved. You are on the right track and adjusting your float level and rechecking your needle and seat are the way to go. By the way, the Yamaha oil pump is adjustable, but I wouldn't mess with it unless you oil foul plugs.

Ken
 

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Discussion Starter #20
THANK YOU KEN!!! dang...didn't think anybody on here agreed with me!! i took everything apart again today, adjusted the float level on the right side, fired it off...both cylinders firing perfectly. i adjusted the idle (one was barely hitting, the other going fast) and took it for a spin. i forgot that there was hardly any gas in the bike after we drained the tank to remove it and checked the coild (probably had a quart in the tank) and i ran out of gas on my 7 mile test run, but it ran great up till then, and it quit on me about a 10th of a mile from the house, on top of a hill, so i just coasted home...no biggy. i fueled it up, it fired right off again, but i didnt go for another test ride because it was dark and i don't trust the bike enough to say "oh i won't get stranded" im going to test it the next 3 days and make sure its fit before i decide whether or not i take it to the GP in indy. but right now, systems seem to be a go. oh, i also adjusted the air screw on both carbs, 2 turns out...and im running a 140 jet with a 8 plug. for you 2 stroke guys, even though i was a die hard NGK ES plug user, i HIGHLY recommend the EV plugs now. ES's don't clean theirselves up after a screw up like the EV's do. when i got back to the house, the plugs were a light tan, so i was thinking a SHADE lean, till i remembered that a motor will go lean when you run them out of fuel...LOL. so as of now, i think i'm pretty close on getting this. i cleaned up, hopped in the truck and went to enjoy some celebratory beer with my buddy who was over here yesterday helping me tune. this feels pretty good and i'm hoping that i'll be in indy on the thing!!
 
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