Hanging RPM Issue

Spitfire · 26th March 2009, 11:42

Is it the stock carb?

This shouldnt happen due to low level of fuel. Stock jets?

reddy6980 · 26th March 2009, 11:54

Maybe this is a Silly answer but i think your choke was on.Try the same thing now with your choke pulled it will produce the same results.

praJEEP · 26th March 2009, 14:54

MY weird guess ! try and give the accelator cable separate route, oe route is along with the clutch cable.

Sankar · 26th March 2009, 14:57

Quote:

Originally Posted by Spitfire

Is it the stock carb?

This shouldnt happen due to low level of fuel. Stock jets?

Nope it's a TM32. It can happen due to low fuel flow. The main jet is set deep down in the bowl and there's much height difference (compared to any other carb available locally) between the pilot jet placement and main jet. I was running on midrange circuit mostly on that day and often had to partly close the throttle. While i was in the midrange circuit the fuel is being metered by jetneedle sucked through the deep set mainjet. So even with low fuel flow the main is still submerged in fuel and since i wasn't on WOT the level dint deplete fast so as to notice fuel starvation, fuel was still flowing so as to keep the main submerged but not enough to keep the level steady. But when throttle is closed pilot circuit is activated and since the fuel flow couldn't keep up with demand pilot jet will not have proper level around it, leaning it out.

I know it's all theory but that is the only sensible explanation i have and it seems sensible enough. The problem is solved i dint do anything to solve it

A turn to reserve fixed that and then i topped up the tank and now running fine on ON.

The float bowl of this carb is huge! I can travel a little more than a kilometre with fuel tap closed if i ride it sensibly. On stock carb it was less than half a kilometre.

Quote:

Originally Posted by reddy6980

Maybe this is a Silly answer but i think your choke was on.Try the same thing now with your choke pulled it will produce the same results.

Choke would make the bike 8stroke and bog down. It will not cause the RPM to hang.

Quote:

Originally Posted by praJEEP

MY weird guess ! try and give the accelator cable separate route, oe route is along with the clutch cable.

Throttle cable is free.. it's not sticking anywhere!
It's solved. Fuelled up the tank.

kuttapan · 27th March 2009, 00:34

Quote:

Originally Posted by Sankar

Nope it's a TM32. It can happen due to low fuel flow. The main jet is set deep down in the bowl and there's much height difference (compared to any other carb available locally) between the pilot jet placement and main jet. I was running on midrange circuit mostly on that day and often had to partly close the throttle. While i was in the midrange circuit the fuel is being metered by jetneedle sucked through the deep set mainjet. So even with low fuel flow the main is still submerged in fuel and since i wasn't on WOT the level dint deplete fast so as to notice fuel starvation, fuel was still flowing so as to keep the main submerged but not enough to keep the level steady. But when throttle is closed pilot circuit is activated and since the fuel flow couldn't keep up with demand pilot jet will not have proper level around it, leaning it out.

Fuel flow which does not restrict the bike on main jet circuit, but starves on pilot jet circuit? I don't know why, but I find that explanation hard to buy. Now, I have not seen a TM32 carb and you probably know better, but I think there has to be a different explanation to the hanging rpm issue.

rider60 · 27th March 2009, 00:51

well to make sure there we rule out other probabilities as well for later on, try and get the Green-Cotton cleaning kit instead of the K&N's, atleast get the oil spray can from Green, PETE's would sell you this.

that way you can make sure you put in just enough oil on to the filter, back in the picture the filter looked a little less on the oil, the sprayer works like a charm instead of the K&N's oil pouring on line by line, and this thing spreads very evenly to top it off the Green-Cotton recharge KIT from PETE's performance products costs almost 30% lesser incomparison to K&N, i have used them both and i Prefer Green's for the convenience of cleaning and recharging!

Sankar · 27th March 2009, 07:55

Quote:

Originally Posted by kuttapan

Fuel flow which does not restrict the bike on main jet circuit, but starves on pilot jet circuit? I don't know why, but I find that explanation hard to buy. Now, I have not seen a TM32 carb and you probably know better, but I think there has to be a different explanation to the hanging rpm issue.

Hehehe... yeah i don't have a better explanation myself man!

Yesterday while riding back home, i put the fuel tap in off position to simulate running out of fuel scenario and the RPM did hang! But since the fuel wasn't flowing at all (as compared to low fuel flow) it went into fuel starvation mode a lil too soon after hanging RPM.

Quote:

Originally Posted by rider60

well to make sure there we rule out other probabilities as well for later on, try and get the Green-Cotton cleaning kit instead of the K&N's, atleast get the oil spray can from Green, PETE's would sell you this.

that way you can make sure you put in just enough oil on to the filter, back in the picture the filter looked a little less on the oil, the sprayer works like a charm instead of the K&N's oil pouring on line by line, and this thing spreads very evenly to top it off the Green-Cotton recharge KIT from PETE's performance products costs almost 30% lesser incomparison to K&N, i have used them both and i Prefer Green's for the convenience of cleaning and recharging!

I know man, i like Green cotton compared to K&N. I had a Green on the Enfield but someone nicked it, that's when i bought K&N. Green is definitely more value. I need a bigger filter since the K&N is a stretch fit, so will buy the kit alongwith the filter. The pic you saw is not of the filer in it's present condition, it has been cleaned and oiled after that.

rahulsingh007 · 27th March 2009, 20:07

I think I am having the same problem.
When ever I press the clutch the RPM stays at 2K- 3k
Wht shall I do

Sankar · 27th March 2009, 20:13

Well... the issue is not solved. Again i had the RPM hangin while returning today evening.

This time the rpm dint fall when i pulled in the clutch... so my whole theory of fuel level and crap have been flushed down the throne.

So got to think fresh. Lemme check for any airleak.

kuttapan · 28th March 2009, 04:51

Leak sounds very probable, but shouldn't idling be higher as well? Or is it a leak that manifests itself only when the bike is hot?

Sankar · 28th March 2009, 08:49

Yep, got to see. I adjusted the idling circuit a bit, the airscrew was a bit too lean compared to earlier settings. I must've opened it and forgot to turn it back after the experimentation. Lemme see if this solves the problem.

rahulsingh007 · 15th April 2009, 19:34

Did you solve your problem ?
I need to know the solution because I have a similar problem !

Sankar · 16th April 2009, 22:23

Yeah i did manage to solve it. The problem was air leak at the manifold caused due to the use of stock manifold with an oversized carb. So no matter how well i tightened the manifold around the carb it still used to develop a small leak after couple of days. So this time used RTV silicone in the manifold and inserted the carb and tightened it down. It will not leak, has been good since a week now.

26th March 2009, 11:42	#16
Spitfire BANNED Join Date: Jul 2006 Location: Panaji - Goa/Bangalore - Karnataka Posts: 3,312 Thanked: 774 Times	Is it the stock carb? This shouldnt happen due to low level of fuel. Stock jets?
	() Thanks

26th March 2009, 11:54	#17
reddy6980 BHPian Join Date: Sep 2005 Location: bangalore Posts: 151 Thanked: 44 Times	Maybe this is a Silly answer but i think your choke was on.Try the same thing now with your choke pulled it will produce the same results.
	() Thanks

26th March 2009, 14:54	#18
praJEEP BHPian Join Date: Aug 2007 Location: Bengaluru Posts: 537 Thanked: 8 Times	MY weird guess ! try and give the accelator cable separate route, oe route is along with the clutch cable.
	() Thanks

27th March 2009, 00:51	#21
rider60 Senior - BHPian Join Date: Mar 2007 Location: Bhagyanagaram. (A.K.A. Hyderabad) Posts: 1,620 Thanked: 56 Times View My Garage	well to make sure there we rule out other probabilities as well for later on, try and get the Green-Cotton cleaning kit instead of the K&N's, atleast get the oil spray can from Green, PETE's would sell you this. that way you can make sure you put in just enough oil on to the filter, back in the picture the filter looked a little less on the oil, the sprayer works like a charm instead of the K&N's oil pouring on line by line, and this thing spreads very evenly to top it off the Green-Cotton recharge KIT from PETE's performance products costs almost 30% lesser incomparison to K&N, i have used them both and i Prefer Green's for the convenience of cleaning and recharging!
	() Thanks

27th March 2009, 20:07	#23
rahulsingh007 BHPian Join Date: May 2008 Location: Amritsar Posts: 164 Thanked: 44 Times	I think I am having the same problem. When ever I press the clutch the RPM stays at 2K- 3k Wht shall I do
	() Thanks

27th March 2009, 20:13	#24
Sankar Senior - BHPian Join Date: May 2005 Location: Location Posts: 5,766 Thanked: 9,053 Times	Well... the issue is not solved. Again i had the RPM hangin while returning today evening. This time the rpm dint fall when i pulled in the clutch... so my whole theory of fuel level and crap have been flushed down the throne. So got to think fresh. Lemme check for any airleak.
	() Thanks

28th March 2009, 04:51	#25
kuttapan Senior - BHPian Join Date: May 2007 Location: Melbourne Posts: 1,155 Thanked: 22 Times View My Garage	Leak sounds very probable, but shouldn't idling be higher as well? Or is it a leak that manifests itself only when the bike is hot?
	() Thanks

28th March 2009, 08:49	#26
Sankar Senior - BHPian Join Date: May 2005 Location: Location Posts: 5,766 Thanked: 9,053 Times	Yep, got to see. I adjusted the idling circuit a bit, the airscrew was a bit too lean compared to earlier settings. I must've opened it and forgot to turn it back after the experimentation. Lemme see if this solves the problem.
	() Thanks

15th April 2009, 19:34	#27
rahulsingh007 BHPian Join Date: May 2008 Location: Amritsar Posts: 164 Thanked: 44 Times	Did you solve your problem ? I need to know the solution because I have a similar problem !
	() Thanks

16th April 2009, 22:23	#28
Sankar Senior - BHPian Join Date: May 2005 Location: Location Posts: 5,766 Thanked: 9,053 Times	Yeah i did manage to solve it. The problem was air leak at the manifold caused due to the use of stock manifold with an oversized carb. So no matter how well i tightened the manifold around the carb it still used to develop a small leak after couple of days. So this time used RTV silicone in the manifold and inserted the carb and tightened it down. It will not leak, has been good since a week now.
	() Thanks