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"VIDEO" New TM40 Carb and still have same issues as stock carb

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alright, got the new TM40 carb bolted in and the first issue i ran into was fuel line running because i wasn't sure how anybody else did it, then i ran into throttle adjustment issues. cables didn't have much slack in them. and now that it is running i still have a problem

Hanging idle. i can get it to idle, but when i blip the throttle it hangs at about 3600rpm and doesn't seem to care to come down any. the other issue that i heard was when it was idling, it had a POP sound from the airbox and then it died. i have some videos and you can't really hear the POP but it is there.

when i put a new cam and rockers in last winter i believe it may have had lack of oiling causing the rockers to destroy themselves. i'm just kind of wondering if maybe i have a bent valve that is causing the POP and hanging idle.

Hangin idle

idle POP

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Is it supposedly jetted correctly for your 650r straight out of the box???

I've watched both the vids..That pop is not abnormal,,unless my 86 XR600 with the stock carbs also has a bent valve which I don't think it does..It does that a lot before it's fully warmed up ((pops through the rear of the carb and dies)),, I think my reason is I'm still lean on the Pilot..Rest of the high idling thing I wouldn't know apart from saying I had a used Mikuni Flatslide ((edit Roundslide)) that did that and it was caused by the idle screw marking the slide and the screws tip also being dodgy thus not allowing a clean movement..Yours of course is new so ,,dunno..Did you apply any lube (CRC maybe) to the slide outer walls..

We assume the cablings good and you have plenty of play everywhere??

Have you tried things with the Tank off,,ie sit it up out of the way of the cables and give it a go..you may need a longer hose to try that ,,or,, fill the carb from the Tank then remove the tank,,start it,,then let it run dry on what's in the carb..Jiggle cabling as it runs and see if it affects things..

Edited by Horri

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it was supposedly jetted correctly or pretty dang close. i didn't lube the slide with anything. cabling is all new. got it from powerbarn. not much freeplay at all in the cables as i got it running first and adjusted the idle to where it "needed" to be and havn't gone back to finalize the adjustment. the whole reason i got the TM40 was because i thought i could easily solve my hanging idle that i had with the stocker carb. little did i know.....

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is it anew or used carb?in the first video your idle is set way to low.

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You might have a point on a possible valve leak. A "hanging idle" can seem the same as a leaking valve. As a carb is adjusted up for the compensation for the leaking valve you will then have "high idle" then as the idle comes down there is no complete combustion,thus;'pop and stall'. You need a cylinder leak down test to be sure. (No compression test will help.)

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It sounds like the throttle is stuck open. When you roll off the throttle, can you visually see that the cable is returning all the way and the slide is closed? Are you running both cables on the carb or just the one?

I don't think they come jetted perfectly straight out of the box, it should be close if you have given them the set up of your bike but will probably still need a tweak.

You should probably get the jetting specs and post them up. Could help to problem solve as well as add to the data base of specs that guys post up of their carb jetting:thumbsup:

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like i said, i did get it from powerbarn and they supposedly put in the correct or "close to" jets for my bike and altitude and temp. i don't think that the hang up is caused by the throttle tube/cables because the slide is fully returning, and cables are brand new as part of the kit from powerbarn. although this all started happening when i installed http://www.denniskirk.com/jsp/product_catalog/Product.jsp?skuId=594852&store=Main&catId=&productId=p594850&leafCatId=&mmyId=566 it was on the list of things that i did while waiting to install the new stage 1 hotcams. i'm not sure what jets are actually in it as i was too excited to install it, so i didn't even look before installing. i will have to take a good look tomorrow after work and post the jets. from what i've read it would need to be pretty close to

PJ - 22.5

AJ - 1.2

JN - 9DJY2

NJ - Y-4

Main - 140

from the other jets that i did get when i got it i received a Pilot of 22.5 and 27.5 making me believe that it has a 25 installed and main of 140, 142.5, 147.7, and 150. making me believe that it has a 145 installed. as far as the others. i would have to look.

as far as mods go. uncorked, twin air, hotcams Stage 1. stock exhaust 900ft and averaging of 60 - 80 degrees

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went to the garage quick....

145 main

25 pilot

Y4 Needle Jet

9DJY1 Jet needle

1.1 air jet

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Speaking strictly about the jetting and not the idle issue your setup is pretty close. You'll actually want to try a 137.5 main and the needle on clip 4. If you don't have the #45 pump nozzle you should pick one up and install it. You also need to make sure the spray is hitting the needle correctly. What's your fuel screw at?

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Speaking strictly about the jetting and not the idle issue your setup is pretty close. You'll actually want to try a 137.5 main and the needle on clip 4. If you don't have the #45 pump nozzle you should pick one up and install it. You also need to make sure the spray is hitting the needle correctly. What's your fuel screw at?

i'm not too concerned about anything but the pilot circuit as of now. i need to figure that out and get rid of the idle hanging before i move on.

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It sounds like there may be an air leak/crack somewhere on the intake boot. :thumbsup:

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I had the same popping coming from the air box, it sounded like a carby backfire so to speak.

It had a 22.5 pilot jet and use to stall(after popping), about 5 times in about a minutes time.

I then put a 25 pilot jet and then the stalling happened maybe 2 times in a minute(until warmed up)

I now have a 27.5 pilot jet and the popping is almost all gone, it might pop once in a blue moon when cold, so i think its still running a bit lean and will be going to a 30 PJ soon.

Try that 27.5 you have, it might be enough to almost fix it, however with a cam it might need it richer even more.

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It sounds like there may be an air leak/crack somewhere on the intake boot. :thumbsup:

the boot is about as tight as i can get it, not sure where else air could be getting in at. i'll take it apart tonight when i put bigger pilots in and clean it all up nice and maybe put some new hose clamps on it.

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Did the engine have any of these symptoms with the original carb?

Does the new carb have an idle mixture adjustment screw?

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Did the engine have any of these symptoms with the original carb?

Does the new carb have an idle mixture adjustment screw?

the engine had the exact issues with the original carb. as far as the idle, then revving it up a bit then it getting stuck at 3500rpm. yes it has a fuel mix screw. i plan on getting some different jets after work and trying my luck with these.

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Guess I'm confused or perhaps misunderstanding?

If your stock carb had the same symptoms as them tm40 then logically it would point to something other than the carb.

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Guess I'm confused or perhaps misunderstanding?

If your stock carb had the same symptoms as them tm40 then logically it would point to something other than the carb.

that is correct. that is what i'm trying to figure out.

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that is correct. that is what i'm trying to figure out.

Spray some carb cleaner all arround the boots and intake......you have a vacuum leak almost guaranteed.....use carb cleaner with the long nozzle to pinpoint the leak......

B

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Spray some carb cleaner all arround the boots and intake......you have a vacuum leak almost guaranteed.....use carb cleaner with the long nozzle to pinpoint the leak......

B

I think he's already done that... (from a different post)

That would by my guess though. for it to modify the engine's running it has to be AFTER the carb. (the little connector boot).

If all else fails, sell me the carb =)

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