Shimmed, choke now kills engine

rustler753 · September 26th, 2009, 06:10 PM

So I did 1 shim in each carb, the bike rides great, starts in even colder weather, but now that winter is coming around, I would like to use the choke. Problem is that any amount of choke after the shim will allow the engine to start, but it slowly will go down to 0 rpms and die in about 10sec. Whats up with that?

kkim · September 26th, 2009, 06:12 PM

does it start with no choke at all when cold? if so, what happens?

rustler753 · September 26th, 2009, 07:03 PM

Quote:

Originally Posted by kkim

does it start with no choke at all when cold? if so, what happens?

Oh it'll start with no choke, but if its really cold out, it will go to 500-1000k rpms, and die a few secs later. I need the choke for when it gets 30F-40F, but using the choke will cause it to start right up in fact, but it wont maintain rpms.

kkim · September 26th, 2009, 07:46 PM

How much are you turning the lever... all the way or partial?

rustler753 · September 26th, 2009, 07:58 PM

Quote:

Originally Posted by kkim

How much are you turning the lever... all the way or partial?

Partial to all the way, still dies, like I make the fuel too rich even the slightest and then it stalls.

kkim · September 26th, 2009, 08:10 PM

do you have the proper amount of freeplay at the linkage end of the choke cable down by the carbs?

rustler753 · September 26th, 2009, 09:51 PM

Quote:

Originally Posted by kkim

do you have the proper amount of freeplay at the linkage end of the choke cable down by the carbs?

How do I check that? Also the choke worked fine before I did my shimming, would the freeplay need to be changed after adding a shim?

kkim · September 27th, 2009, 12:01 AM

take a look in your owner's manual on how to set the choke cable free play. you had to take a screw off that holds one of the cable brackets to take off the carb tops when you shimmed. perhaps you put it back on a bit off??

rustler753 · September 27th, 2009, 01:24 AM

Quote:

Originally Posted by kkim

take a look in your owner's manual on how to set the choke cable free play. you had to take a screw off that holds one of the cable brackets to take off the carb tops when you shimmed. perhaps you put it back on a bit off??

I checked the bolting, brackets seem to be where they are supposed to be. Ever heard of the problem before?

kkim · September 27th, 2009, 01:27 AM

sorry. no, I have not. If nothing is wrong mechanically, I have a strong suspicion it has something to do with altitude. How high is it where you are located?

rustler753 · September 27th, 2009, 01:29 AM

Quote:

Originally Posted by kkim

sorry. no, I have not. If nothing is wrong mechanically, I have a strong suspicion it has something to do with altitude. How high is it where you are located?

Boulder, Colorado. 5,430 FT, pretty high. I mean the bike looooves the shims, starts up where I had to use full choke for like even 60F.

Nevrfastenuf · September 27th, 2009, 08:17 AM

Mike

My bike does a very similar thing to what you have explained. I am still learning myself, but let me share what my experience has been in case it helps you in any way. I am a little lower in altitude where I live, but I ride in the 5000' to 10000' range. After I picked a main jet and decided on the number of shims that worked best for me I started working on the pilot setting. That's when I ran into the problem you described. If I tuned the idle or midrange (pilot or shims) to work well then I kept running into a situation where it felt like a had a small lean surge when cruising at freeway speeds when I was turning the throttle just enough to maintain my speed. After trying many different combinations of pilot and shim combinations I feel that it may possibly be a result of the stock needles taper. The pictures I have seen of the stock vs. a dyno jet needle show a longer tapered area on the dyno jet needle. I think the shorter stock taper is causing my bike to experience a temporary lean spot as it transitions from the pilot circuit to the needle circuit. Next spring I will buy some new needles to see if it really will fix my problem, until then, the bike runs great with the pilot being just a little rich.

Now that the mornings are getting a little colder I have noticed that it needs a little choke to get it going. My starting process is to start it with no choke, then pull the choke lever just enough to get the rpm to rise a bit, if I pull the lever too far it dies. Even on 40 degree mornings I only need that small amount of choke lever for maybe 60 seconds and then I let it idle with the choke lever completely off for a few more minutes while I put my gear on.

Hope this helps, enjoy the rest of the wonderful fall riding weather

g21-30 · September 27th, 2009, 08:32 AM

Mike and Clint,

Post #13 details with 2 examples where the different carb circuits play a vital role in the performance of the bike.

http://www.ninjette.org/forums/showthread.php?t=10246

Nevrfastenuf · September 27th, 2009, 09:18 AM

Quote:

Originally Posted by g21-30

Mike and Clint,

Post #13 details with 2 examples where the different carb circuits play a vital role in the performance of the bike.

http://www.ninjette.org/forums/showthread.php?t=10246

Very nice, thanks for finding that

The chart I had seen wasn't as detailed and had lumped a few things in each area together. Looks like trying out different diameter needles will need to be put on the to-do list for next spring so I can hopefully get the idle leaned out just a bit without making it too lean in the 1/8 to 1/4 throttle area.

g21-30 · September 27th, 2009, 10:10 AM

Quote:

Originally Posted by Nevrfastenuf

Looks like trying out different diameter needles

I think you will be spinning your wheels (wasting time) fooling with the needle taper; however, we all know about opinions.

Having said that, experimentation is a good thing, as that's how we learn. Don't let me discourage your needle taper research!

Dynojet and Factory Pro have pretty well already perfected the needle tapers, so that all we need to do is experiment with the jet sizes. As I've mentioned in other threads, Area P used DJ for development with their exhaust system and that's what they sell.

Good luck with whatever you decide to do! Just let us know the results.

g21-30 · September 27th, 2009, 10:26 AM

Quote:

Originally Posted by rustler753

How do I check that? Also the choke worked fine before I did my shimming, would the freeplay need to be changed after adding a shim?

kkim · September 27th, 2009, 11:41 AM

If you have the mixture screw caps off the carbs, adjusting the mixture screws may yield you both some better results.

I would be reluctant to play with needle tapers as that can get expensive and confusing after awhile unless you really know what you are doing. Make the incorrect needle choice and there is a chance of motor damage.

Nevrfastenuf · September 27th, 2009, 11:58 AM

Quote:

Originally Posted by kkim

If you have the mixture screw caps off the carbs, adjusting the mixture screws may yield you both some better results.

I would be reluctant to play with needle tapers as that can get expensive and confusing after awhile unless you really know what you are doing. Make the incorrect needle choice and there is a chance of motor damage.

Not to mention I've found that needle prices are outrageous! I think I'll just pick up a dynojet kit over the winter and be done with it

NorCal_250R · September 28th, 2009, 09:14 AM

I can personally recommend the Factory Pro jet kit...the needle taper on the FP needles is very good.
The kit comes with the needles, bigger pilot gets (40) instead of 38 I think...plus an assortment of mains from 88 to 110s...
Factory doesn't recommend drilling the slides like in the Dynojet kit, but that it only their professional judgement...

rustler753 · September 28th, 2009, 02:13 PM

Should I have my carbs synced? Any amount of choke kills the rpms, I wouldn't have the tools to check the carb adjustment screws, can I bring it to my dealership with out them yelling at me for the shims ( if they would even notice). If it keeps up, I'll just have to pull out the shims when I get a chance, because colder and colder weather is rolling in.

kkim · September 28th, 2009, 02:20 PM

you can try syncing, but I don't think that's the problem.... wouldn't hurt, if you have the tools to do so.

The dealership is not supposed to play with the mixture screws, so most likely you wouldn't be able to get any help from them. You can ask, though. If they yell at you, tell them to shove it where the sun don't shine and find another dealer that knows how to deal with their customers w/o yelling at them. Yelling is not an acceptable business practice in my book.

karlosdajackal · September 29th, 2009, 01:04 AM

before shims = no problem
after shims = problem

is it to obvious to say that you don't need the shims, your bike is running too rich and when you add some choke it runs to rich and stalls. Sounds to me like the shims are making it far too rich, effectively its like always having the choke pulled.

If you bike needs full choke to start without the shims that's not a bad thing at that altitude, choke is there to be used and turned off when you have it up to temperature. You should not be aiming to get the bike to never need choke under those conditions, as if you are succesful it will just mean its too rich the rest of the time.

I vote to remove the shims that create the problem.

September 27th, 2009, 08:17 AM	#12
Nevrfastenuf ninjette.org member Name: Clint Location: Utah Join Date: Aug 2009 Motorcycle(s): 2009 ER-6n 2009 Ninja 250 sold :( Posts: 61	Mike My bike does a very similar thing to what you have explained. I am still learning myself, but let me share what my experience has been in case it helps you in any way. I am a little lower in altitude where I live, but I ride in the 5000' to 10000' range. After I picked a main jet and decided on the number of shims that worked best for me I started working on the pilot setting. That's when I ran into the problem you described. If I tuned the idle or midrange (pilot or shims) to work well then I kept running into a situation where it felt like a had a small lean surge when cruising at freeway speeds when I was turning the throttle just enough to maintain my speed. After trying many different combinations of pilot and shim combinations I feel that it may possibly be a result of the stock needles taper. The pictures I have seen of the stock vs. a dyno jet needle show a longer tapered area on the dyno jet needle. I think the shorter stock taper is causing my bike to experience a temporary lean spot as it transitions from the pilot circuit to the needle circuit. Next spring I will buy some new needles to see if it really will fix my problem, until then, the bike runs great with the pilot being just a little rich. Now that the mornings are getting a little colder I have noticed that it needs a little choke to get it going. My starting process is to start it with no choke, then pull the choke lever just enough to get the rpm to rise a bit, if I pull the lever too far it dies. Even on 40 degree mornings I only need that small amount of choke lever for maybe 60 seconds and then I let it idle with the choke lever completely off for a few more minutes while I put my gear on. Hope this helps, enjoy the rest of the wonderful fall riding weather __________________________________________________ "Never argue with an idiot, they will just drag you down to their level and beat you with experience" -Unknown

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September 26th, 2009, 06:10 PM	#1
rustler753 ninjette.org member Name: Mike Location: Boulder, CO Join Date: Jun 2009 Motorcycle(s): 09' Ninja 250 (SOLD); 00' CBR 929RR Posts: 133	Shimmed, choke now kills engine So I did 1 shim in each carb, the bike rides great, starts in even colder weather, but now that winter is coming around, I would like to use the choke. Problem is that any amount of choke after the shim will allow the engine to start, but it slowly will go down to 0 rpms and die in about 10sec. Whats up with that?

September 26th, 2009, 06:12 PM	#2
kkim Join Date: Nov 2008 Posts: Too much.	does it start with no choke at all when cold? if so, what happens?

September 26th, 2009, 07:46 PM	#4
kkim Join Date: Nov 2008 Posts: Too much.	How much are you turning the lever... all the way or partial?

September 26th, 2009, 08:10 PM	#6
kkim Join Date: Nov 2008 Posts: Too much.	do you have the proper amount of freeplay at the linkage end of the choke cable down by the carbs?

September 27th, 2009, 12:01 AM	#8
kkim Join Date: Nov 2008 Posts: Too much.	take a look in your owner's manual on how to set the choke cable free play. you had to take a screw off that holds one of the cable brackets to take off the carb tops when you shimmed. perhaps you put it back on a bit off??

September 27th, 2009, 01:27 AM	#10
kkim Join Date: Nov 2008 Posts: Too much.	sorry. no, I have not. If nothing is wrong mechanically, I have a strong suspicion it has something to do with altitude. How high is it where you are located?

September 27th, 2009, 08:32 AM	#13
g21-30 ninjette.org certified postwhore Name: Sam Location: Northern Virginia Join Date: Nov 2008 Motorcycle(s): Ninja 250R 2009 Posts: A lot.	Mike and Clint, Post #13 details with 2 examples where the different carb circuits play a vital role in the performance of the bike. http://www.ninjette.org/forums/showthread.php?t=10246

September 27th, 2009, 11:41 AM	#17
kkim Join Date: Nov 2008 Posts: Too much.	If you have the mixture screw caps off the carbs, adjusting the mixture screws may yield you both some better results. I would be reluctant to play with needle tapers as that can get expensive and confusing after awhile unless you really know what you are doing. Make the incorrect needle choice and there is a chance of motor damage.

September 28th, 2009, 09:14 AM	#19
NorCal_250R ninjette.org member Name: Jordan Location: Corte Madera Join Date: Jun 2009 Motorcycle(s): 06 Ninja 650R, 08 Ninja 250R, 00 Aprilia SR50 (dead) Posts: 94	I can personally recommend the Factory Pro jet kit...the needle taper on the FP needles is very good. The kit comes with the needles, bigger pilot gets (40) instead of 38 I think...plus an assortment of mains from 88 to 110s... Factory doesn't recommend drilling the slides like in the Dynojet kit, but that it only their professional judgement...

September 28th, 2009, 02:13 PM	#20
rustler753 ninjette.org member Name: Mike Location: Boulder, CO Join Date: Jun 2009 Motorcycle(s): 09' Ninja 250 (SOLD); 00' CBR 929RR Posts: 133	Should I have my carbs synced? Any amount of choke kills the rpms, I wouldn't have the tools to check the carb adjustment screws, can I bring it to my dealership with out them yelling at me for the shims ( if they would even notice). If it keeps up, I'll just have to pull out the shims when I get a chance, because colder and colder weather is rolling in.

September 28th, 2009, 02:20 PM	#21
kkim Join Date: Nov 2008 Posts: Too much.	you can try syncing, but I don't think that's the problem.... wouldn't hurt, if you have the tools to do so. The dealership is not supposed to play with the mixture screws, so most likely you wouldn't be able to get any help from them. You can ask, though. If they yell at you, tell them to shove it where the sun don't shine and find another dealer that knows how to deal with their customers w/o yelling at them. Yelling is not an acceptable business practice in my book.

September 29th, 2009, 01:04 AM	#22
karlosdajackal ninjette.org guru Name: Karl Location: Ireland the Hawaii of Europe! Join Date: Jun 2009 Motorcycle(s): Ninja 250R Fuel Injected Model 2009 Posts: 357	before shims = no problem after shims = problem is it to obvious to say that you don't need the shims, your bike is running too rich and when you add some choke it runs to rich and stalls. Sounds to me like the shims are making it far too rich, effectively its like always having the choke pulled. If you bike needs full choke to start without the shims that's not a bad thing at that altitude, choke is there to be used and turned off when you have it up to temperature. You should not be aiming to get the bike to never need choke under those conditions, as if you are succesful it will just mean its too rich the rest of the time. I vote to remove the shims that create the problem.