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idling speed when engine is hot

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idling speed when engine is hot

Postby snezana » Sat Jul 21, 2018 4:17 pm

Hi, Can anyone help me with the reasons why the idle speed on my 1982 GP200 rises when the engine is hot. It has a standard barrel,piston, 22mm jetex carb with a 118 main jet and recently I have fitted a TSR Evo exhaust, 19 tooth front sprocket 46 tooth rear Clutch sprocket. There are no leaks on the inlet side, plug colour is chocolate brown.

I have fitted a fast flow air filter and NGK 7 grade plug. It starts 2nd kick everytime from cold and first kick when hot, no smoke fom the exhaust.

Any ideas?

Paul.
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Re: idling speed when engine is hot

Postby MickYork » Sat Jul 21, 2018 4:29 pm

An air leak would be my guess, but it might only materialise when hot (expansion of parts)

what is your timing set at and have you checked it (strobed) ?
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Re: idling speed when engine is hot

Postby snezana » Sat Jul 21, 2018 4:54 pm

Hi Mick,

I have checked all the inlet side for leaks the best that I can, I have recently had my Stator plate repaired (broken earth) and re-fitted it in the origional location.
I have suspected timing but have not set it up with a strobe lamp. As it starts so easily I had not really realised it could be timing.
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Re: idling speed when engine is hot

Postby MickYork » Sat Jul 21, 2018 7:07 pm

a too much advanced timing/stator will make it easier to start but will run dangerously lean........
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Re: idling speed when engine is hot

Postby missing lynx » Sun Jul 22, 2018 4:43 am

when you say hot do you mean when the engine is at normal running temp if it is then that's the temp you should set the tick over not when the engine is cold. sorry if I'm teaching you to suck eggs
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Re: idling speed when engine is hot

Postby CHRIS in MARGATE » Sun Jul 22, 2018 6:57 am

How high has it risen? It may have.just reached normal operating temperature and that as stated is when to set tickover speed.
If you rev it.on the stand when it's warm does it respond well and settle back instantly to a steady tickover or does it race a bit for a while. If that is happening then that is a sign of weak mixture.
You.put a new exhaust on; did you rejet?
Plug colour is only a good indicator at the engine speed over the last couple of minutes so.looking at it after riding into the driveway and letting it tick over for a while can not give you an accurate picture.
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Re: idling speed when engine is hot

Postby col68 » Sun Jul 22, 2018 11:18 am

I just fitted a tsr evo to my tuned ts1 and it needs a lot of fuel now had a franspeed supertourer on had go from a 310 main to a 350 and still wants more . what carb are you using and jetting .
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Re: idling speed when engine is hot

Postby snezana » Sun Jul 22, 2018 3:00 pm

Hi all,
Appreciate all the replys and help,
According to stickys manual SIL put a 123 main jet on later GP200 models, I have looked in the carb this morning as I assumed it had a 118 main jet, I cant see any size marked so am not sure.

I took it it for a run to get it to normal temperature, adjusted the idle to normal speed as suggested and went on another short run, I noticed it is a bit sluggish starting off (gearing is 19/46 on a GP125 box) but after a a few revs it pulls quite well. I dont think it is running as smooth as it should be It has a TSR Evo exhaust is this normal.

I took the plug out and although the tip is brown there is a trace of oil around the edge, I am using a 4% mix with Putoline synthetic oil. I suspect the timing may be incorrect as you have suggested and need to buy a strobe lamp to check it unless you can suggest another method.
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Re: idling speed when engine is hot

Postby missing lynx » Sun Jul 22, 2018 3:33 pm

not wanting to start the correct mix debate I would run it on 3% mix ! it could be as yours is a std 200 barrel and a std 22mm carb the characteristics of the exhaust don't suit my son had a lml 125 wanted a "flash" exhaust he bought a jl and no matter what I tried I couldn't get it to run as well as it did with the sito plus he already had and a strobe is the only way to do timing on an Electronic set up
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Re: idling speed when engine is hot

Postby Toddy » Sun Jul 22, 2018 5:58 pm

The jettex jets are sometimes stamped on the sides rather than on the top like Dellorto ones
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Re: idling speed when engine is hot

Postby snezana » Sun Jul 22, 2018 6:53 pm

Thanks for the Jet size location, I will check again. Just come back from a short run, Its a bit boggy when pulling away in first . Will check the timing as soon as I buy a strobe lamp to determine if its too far advanced. I dont really want to fit a bigger carb as I would prefer it to be as standard as possible apart from the TSR exhaust.

I remember the stator plate position on the old points system had a starting point at mid slot, my electronic stator is currently set at about two thirds clockwise in the slots. I understand the importance of strobe timing just wondering if this seems too far retarded as a starting point or is this close to normal for electronic stators.
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Re: idling speed when engine is hot

Postby CHRIS in MARGATE » Sun Jul 22, 2018 7:43 pm

You can't tell by looking at the slots. You could be several degrees out.
If tickover is now better and stable but it's a little sluggish pulling away you may need to weaken the air screw a little.
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Re: idling speed when engine is hot

Postby snezana » Sun Jul 22, 2018 8:00 pm

Tickover is better after setting the idle when up to temperature, will do as you suggest and weaken it a little. I have returned to scootering after many years and dont have much experience with the electronic setup. Never too old to learn and hopefully can get a few pointers from the youngsters.
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Re: idling speed when engine is hot

Postby Toddy » Sun Jul 22, 2018 8:03 pm

snezana wrote:Tickover is better after setting the idle when up to temperature, will do as you suggest and weaken it a little. I have returned to scootering after many years and dont have much experience with the electronic setup. Never too old to learn and hopefully can get a few pointers from the youngsters.



Not many youngsters on here :lol: :lol:
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Re: idling speed when engine is hot

Postby snezana » Sun Jul 22, 2018 8:12 pm

Finally got around to setting the timing using a Gunson strobe lamp, timing disc and piston TDC gauge. I set the timing to 19 degrees BTDC and checked it a number of times.
Pick up is so much better and idling is quite steady. I estimate the timing was retarded by 7 degrees.

Should I change the fuel/oil ratio from 20 to 1 and if so what would be the recommended ratio, I noticed the plug has a very slightly oily tip, currently using an NKG B7 plug would a cooler B8 or 9 make any major change. As previously mentioned it is a standard GP200 engine with a TSR exhaust, it has a 123 main jet, what carb would you guys recommend for use with the standard intake hose/filter and choke cable.

It no longer revs higher at idle when hot so it was incorrect timing however to me it sounds as if it is 4 stroking a little, (suspect too much oil in mix) or is this down to the carb not being suitable for the TSR exhaust. When I rev it up it always settles down to idle speed straight away. I am not looking for high performance just reliability and ease of starting etc.

Appreciate the help,

Paul.
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Re: idling speed when engine is hot

Postby Martin s » Fri Nov 09, 2018 10:05 pm

I followed what Adam Winstone had once written about changing the atomiser from a 2 to 4. My stage 4 200 would 4 stroke until the throttle was open wide. Sorted it out. That was with a clubman and standard GP air filter set up. Ran it with 126 main jet.
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Re: idling speed when engine is hot

Postby Fast n Furious » Sat Nov 10, 2018 12:33 am

The 7 grade plug should work fine. Forget an 8 or 9 with your setup.
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Re: idling speed when engine is hot

Postby snezana » Sat Feb 02, 2019 4:32 pm

Fast n Furious wrote:The 7 grade plug should work fine. Forget an 8 or 9 with your setup.

Thanks for the reply, I changed the plug to 7 as you suggested and fitted a 125 main jet, it runs much better now the timing is sorted and it doesnt 4 stroke anymore.

Cheers,

Paul.
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Re: idling speed when engine is hot

Postby snezana » Sat Feb 02, 2019 4:39 pm

Martin s wrote:I followed what Adam Winstone had once written about changing the atomiser from a 2 to 4. My stage 4 200 would 4 stroke until the throttle was open wide. Sorted it out. That was with a clubman and standard GP air filter set up. Ran it with 126 main jet.

Sorry for the late reply , had a big op and have been off the road a few months.

I have read that drilling holes in the airfilter box also helps with improved airflow, I will try that and see if the mixture and plug colour stay the same.

Cheers,

Paul.
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Re: idling speed when engine is hot

Postby ULC Soulagent » Sat Feb 02, 2019 5:58 pm

snezana wrote:
Martin s wrote:I followed what Adam Winstone had once written about changing the atomiser from a 2 to 4. My stage 4 200 would 4 stroke until the throttle was open wide. Sorted it out. That was with a clubman and standard GP air filter set up. Ran it with 126 main jet.

Sorry for the late reply , had a big op and have been off the road a few months.

I have read that drilling holes in the airfilter box also helps with improved airflow, I will try that and see if the mixture and plug colour stay the same.

Cheers,

Paul.

I wouldn’t bother with doing that for very little gain. Bgm do a nice airbox with performance filter if you fancy splashing £130 odd
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