85 R after carb tune

[Afrothunderkat]

Still a bit of sputter when it's clamped, impressed with the power addition the flat slide added. Way more bottom-mid. Next thing to do is a head gasket, leaks coolant when cold!

Filmed one of the 20 somthing tests with my phone

[bkm]

You shouldn't be leaking coolant out of the base gasket. Did you mean headgasket?

[Afrothunderkat]

You shouldn't be leaking coolant out of the base gasket. Did you mean headgasket?

Base of the jug, head gasket yeah!

[barnett468]

Hello

Still a bit of sputter when it's clamped,

So you are saying it missed at MAX rpm with both the old carb and the new carb. I don’t know about the Honda’s but the Kawi’s have a rev limiter that sounds EXACTLY like that when it is over revved. I’m guessing if you shifted it sooner the problem would go away.

S Next thing to do is a head gasket, leaks coolant when cold!

If water leaks out it can also leak in potentially causing a miss but in your case it seems unlikely. Obviously fix it anyway.


The miss is not likely from jetting but just for fun is your spark plug recent, if so what color is it?

1. white?
2. lite tan?
3. dark tan?
4 dry black?
5 moist gooey black?

[bkm]

Base of the jug, head gasket yeah!

The bottom where it bolts to the lower case, because this is the "base"? This shouldn't leak any coolant. The water passages are sealed off at the bottom of the cylinder. If coolant is leaking from there you have more problems than just a gasket.

The head gasket is on top of the cylinder where the spark plug goes. You need to pull the plug and look and see if it looks like its been steam cleaned. That will tell you if coolant is leaking into the combustion chamber. The gasket may just be leaking to the outside, because there is a metal compression ring on the inside of the gasket keeping coolant out of the chamber.

I'd go back with a thin gasket from a CR250 like 1989 or so. It will bump up compression a little without doing any modifications.

[RIDE-RED 250r]

If you are running anything other than an OEM CDI box, that will be your most likely cause of a top end sputter, stutter or generally crappy running if you are sure the jetting is right!

I can hear the top end sputtering in your vid. Very common issue with aftermarket CDI's. If you are running one, throw it out the window and get an OEM unit on there....

[JasonB]

nice looking R, sounds like your getting it sorted out but it's def sputtering up top. I cant tell if you just have it pinned and thats why its cutting like that or if its not jetted right. Second what barnett said, whats your plug looking like?

[Billy Golightly]

Before you buy a new ignition or ignition parts, make sure you plug is gapped at no more than .018, and squeeze it down to .015 if it still does it. Then you can buy new ingition parts if it still does it

[Afrothunderkat]

Hello, So you are saying it missed at MAX rpm with both the old carb and the new carb. I don’t know about the Honda’s but the Kawi’s have a rev limiter that sounds EXACTLY like that when it is over revved. I’m guessing if you shifted it sooner the problem would go away. If water leaks out it can also leak in potentially causing a miss but in your case it seems unlikely. Obviously fix it anyway.


The miss is not likely from jetting but just for fun is your spark plug recent, if so what color is it?

1. white?
2. lite tan?
3. dark tan?
4 dry black?
5 moist gooey black?

The plug is choco brown, little too much fuel. Never had the issue with the OEM carb. I cleaned the flat slide, jets are.... oddly un-marked or are worn off and i put the need in the middle position, idle air screw is 1 3/4 turns. Also, are you barrnett from Thumpertalk?

The bottom where it bolts to the lower case, because this is the "base"? This shouldn't leak any coolant. The water passages are sealed off at the bottom of the cylinder. If coolant is leaking from there you have more problems than just a gasket.

The head gasket is on top of the cylinder where the spark plug goes. You need to pull the plug and look and see if it looks like its been steam cleaned. That will tell you if coolant is leaking into the combustion chamber. The gasket may just be leaking to the outside, because there is a metal compression ring on the inside of the gasket keeping coolant out of the chamber.

I'd go back with a thin gasket from a CR250 like 1989 or so. It will bump up compression a little without doing any modifications.

Back of the head used to leak where the tabs where, does not anymore. Leaks at the bottom close to the head base gasket (see second pic.) When I do gaskets Ill pick up some cr 250 gaskets, thanks!

If you are running anything other than an OEM CDI box, that will be your most likely cause of a top end sputter, stutter or generally crappy running if you are sure the jetting is right!

I can hear the top end sputtering in your vid. Very common issue with aftermarket CDI's. If you are running one, throw it out the window and get an OEM unit on there....

Not sure if its after market or OEM, I haven't touched it. How do I check?

Nice looking R, sounds like your getting it sorted out but it's def sputtering up top. I cant tell if you just have it pinned and thats why its cutting like that or if its not jetted right. Second what barnett said, whats your plug looking like?

Thanks! You inspired the black rims! Yeah its deff pinned. I was wringing it out to get it to sputter. BTW, your avatar.....DAT ASS

Before you buy a new ignition or ignition parts, make sure you plug is gapped at no more than .018, and squeeze it down to .015 if it still does it. Then you can buy new ingition parts if it still does it

I just got a Br8es in there, I'll have to see about picking up something to gap the plug.

Pictures

[Billy Golightly]

I would also do a leakdown test to see what (if anything) could be up there as well.

[barnett468]

Hello Afrothunderkat


The following is based on my experience only others may vary. In the video your bike does not appear to have a flat spot or miss burble sputter etc. during acceleration, it only misses at max rpm. If this is correct it strongly suggests to me that it is an electrical miss. When a throttle is opened with a bike at mid rpm or less using a traditional siphon [non fuel injection] type carb it runs progressively leaner as the rpm’s build, so if it is stuttering/missing etc. at max rpm because it is too rich it would be even richer in the lower rpm ranges and would therefore stutter/miss even more in that range which would become progressively less as the rpm’s build.

This is what I might do, others would do something else.


SHIFT SOONER - The only other person I have ever seen ring out a 250 like that is Marty Hart when he passed me at a race at Saddleback Park, lol. Although I wouldn’t want my bike to miss at max rpm either, my goodness how much rpm do you guys need. It’s not like it’s missing at 5k rpm, lol.


INSTALL NEW PLUG AND SET GAP – It’s remotely possible your plug is carboned enough to break down at max rpm. Try narrower gap as Billy suggested. Does no one around there have a feeler gauge, that’s all you need?


CARB SETTING - Obviously you know the plug suggests it is a little rich, maybe by 2-3 main jet sizes. This condition can also be caused at least in part by a high float level or a taller than necessary choke height on the needle jet. Since your carb is new as long as it does not burble when transitioning from around 1/8-1/3 throttle your needle jet choke height is close enough. I would put the needle in the middle and drop main by 2 sizes and check plug color again after 30 minutes etc.


IDENTIFYING MAIN JET SIZE AND NO MARKINGS – May be aftermarket jets, nice. Did you buy it used? Find a “number” drill or take jet to a hardware store and find a number drill that fits snugly inside, buy the drill. Tell me what size it is and the maker of your carb [to my “friends”,yes I do know who made the original flat slides] and if I can find my chart I can tell you what size it is. If not simply take the drill to the local motorcycle shop and find one of the same style that fits the drill then buy 2 jets the next size smaller.


CR 250 HEAD GASKET – Since I am not psychic I have no idea what modifications if any have been done to your cylinder and/or head etc therefore I personally would not just arbitrarily install a thinner head gasket, it may cause detonation/pinging etc. which can quickly and easily cause serious damage to your engine. Your bike sounds like it already has port work done to me and ALL PROFESSIONAL cylinder porters will modify your head to get the max compression they can using the octane level of your choice, therefore I suggest doing a compression test using the method suggested by my friend Harry Klemm to determine what you currently have and then determine if you can safely benefit from higher compression and adjust it accordingly. See article in link below.

http://klemmvintage.com/squish&comp.htm


CARB AND HIGH RPM MISS/STUTTER - Since it only has this problem with this carb and I don’t think it is due to a rich condition I’m guessing the carburetor is LARGER than the previous one therefore allowing the engine to rev higher at which an electrical miss occurs. What are the sizes of the previous and current carb?


REV LIMITER – Does anyone know POSITIVELY if this year/model bike has a rev limiter? Has anyone heard one of these with a STOCK CDI that rev’s this far and if so did it miss like this? That question is obviously hard to answer, just curious.


IGNITION COIL – Test by using ohm meter, replace if out of spec. See section 15 in online manual below.

http://www.kb0nly.info/ATC/index.php?dir=ATC250R%2F

Next thing to do is a head gasket, leaks coolant when cold!

Base of the jug, head gasket yeah!

[QUOTE=Afrothunderkat;1227440]Back of the head used to leak where the tabs where, does not anymore. Leaks at the bottom close to the head base gasket (see second pic.)

The photo explains it best, lol. That can still be leaking fluid into your motor but not enough to show up on a plug reading. I would personally think it’s wise to remove cylinder and fix base and head gasket to be safe. Since both obviously leaked at some point either could start spewing ANYTIME. Do a compression test first to see if you can benefit from a thinner head gasket.


BARNETT THUMPERTALK – Nope, that is not me, it is obviously an imposter. The “tell tale” is the style of post. No one can reasonably duplicate my “megaposts”, lol.

one of the 20 somthing tests

That’s a great testament to the quality of that connecting rod, lol.

Filmed

XLNT video and photos, very helpful.

DAT ASS

Yes, JasonB is a fortunate and generous man to share his family photos with us, lol.

[barnett468]

Hello


Post correction/addition


EXHAUST SMOKE AND SPARK PLUG COLOR – I looked at your plug again and enlarged it to 400%. It looks to me to be a4 on my chart with a bit of 5 [sort of in between]. When I combine this with the fact that your bike smokes and the smoke is lite gray it strongly suggests to me that your bike is burning too much oil. This is typically caused by too rich of a gas/oil ratio and/or a [right side in your case] crank seal leak which allows it to suck oil from the gear box into the crankcase.

If this is the same plug and color that it was with your previous carb it is not an accurate representation of how your current carb is jetted or whether it is burning oil or not. I again suggest installing a new plug as I suggested in my previous post.

I agree with Billy Golightly also that you might benefit from doing a “leak down” test to determine if there are any leaks. Your side covers need to be removed to inspect for crank seal leaks if it fails the initial test with the covers on with no visible leaks. Below is a link to a “how to” video.

http://www.youtube.com/watch?v=zdq7NRcUIp8


Most all the 2 stroke motorcycle engines I and the Kawi race teams have run are mixed at a ratio of 32:1. Most oils can be used at this ratio but check yours to be sure. Most oils will not smoke much at this ratio with the possible exception of Castor based oils and most oils including Castor based oils will not cause a plug to turn black like yours at this ratio.

What EXACT 2 stroke oil are you using and what ratio are you mixing it at?


CARB JETTING – Due to my belief that your plug color is due mainly to burning excessive oil I suggest you first adjust your oil ratio then retest with new plug. Drop your main by a maximum 2 only if your plug is a 3 thru 5 on my chart. Install new plug test again change main by 1 if plug suggfests further jetting is required.


SURE WISH I HAD AN EDIT BUTTON

[250r'en +TCB]

Make sure you spray copper gasket on your new head gasket so it seals properly, don't ask me how I know....

[yaegerb]

From what I could barely hear it sounds like its missing. My guess is what billy recommended. Check your plug gap and ensure that your CDI is functioning properly. Chocolate brown on your spark plug is a perfect color FYI, so if that's the case, your carb should be dialed in fairly close.

[Afrothunderkat]

Hello


Post correction/addition


EXHAUST SMOKE AND SPARK PLUG COLOR – I looked at your plug again and enlarged it to 400%. It looks to me to be a4 on my chart with a bit of 5 [sort of in between]. When I combine this with the fact that your bike smokes and the smoke is lite gray it strongly suggests to me that your bike is burning too much oil. This is typically caused by too rich of a gas/oil ratio and/or a [right side in your case] crank seal leak which allows it to suck oil from the gear box into the crankcase.

If this is the same plug and color that it was with your previous carb it is not an accurate representation of how your current carb is jetted or whether it is burning oil or not. I again suggest installing a new plug as I suggested in my previous post.

I agree with Billy Golightly also that you might benefit from doing a “leak down” test to determine if there are any leaks. Your side covers need to be removed to inspect for crank seal leaks if it fails the initial test with the covers on with no visible leaks. Below is a link to a “how to” video.

http://www.youtube.com/watch?v=zdq7NRcUIp8


Most all the 2 stroke motorcycle engines I and the Kawi race teams have run are mixed at a ratio of 32:1. Most oils can be used at this ratio but check yours to be sure. Most oils will not smoke much at this ratio with the possible exception of Castor based oils and most oils including Castor based oils will not cause a plug to turn black like yours at this ratio.

What EXACT 2 stroke oil are you using and what ratio are you mixing it at?


CARB JETTING – Due to my belief that your plug color is due mainly to burning excessive oil I suggest you first adjust your oil ratio then retest with new plug. Drop your main by a maximum 2 only if your plug is a 3 thru 5 on my chart. Install new plug test again change main by 1 if plug suggfests further jetting is required.


SURE WISH I HAD AN EDIT BUTTON

It's not a crank seal, checked it out as my 03 RM 250 had bog issues, thought it was a case seal and replaced. Ended up being too big a jet and running klotz R50.

Thanks for that leak test video, Went out ridding today on my RM and before I left I changed the oil on my 250r. When I pulled myself off the ground using the kicker i heard a "FFFFFFFFT" I look over and its blowing out of where the anti-freeze leaks. You can deff see and hear it just by cranking it over with your hand. Seems to me like a gasket. Im going to take the motor out this week and open her up. I'll take pictures tomorrow.

I use 32:1 klotz 20/80 super techniplate. SMELLS GREAT!

I'll try a new plug after I open her up. I did not touch the jets when i got the carb, Ill do the drill test, and match some jetts up. Also, the trike can idle all day and not load up. Runs real crisp. Something the last carb could not do.

Thanks for the help! I'll keep the thread updated with progress and pictures.