Re: is an engine overhaul necessary??

Thanks bro, I shall wait for the sugestions from experts like you.

Apparently started getting more anxious - as the engine is getting overheated horribly. I understand there are many other factors which result the overheat - but I have tried rectifying the issue with several other measures shuch as
- new genuine pilot jet
- Cleaned the carb thoroughly with solvents and high pressure air
- new OE air filter
- needle in center position as in stock
- Switched to Pre-mix (coz i thought may be the oil pump is working unfit/pumping more oil and causing the mixture LEAN)
- Switched back to auto-lube, as disconnecting the oil pump did no show any improvements
- recommended NGK spark plug.

But eventually the spark plug reading is black (wet oil residue and greasy black).

Re: is an engine overhaul necessary??

First let me clear one thing, i am no expert, just a newbie.
I checked mine its the same like what you have shown in the picture.
But the last line says that your bike is running on the richer side. If it is running lean it should be almost white in colour.
Between, let me ask you one thing. Have you recently rebuild or rebore your cylinder??

Re: is an engine overhaul necessary??

Thanks, Yes I have recently rebored.
But the same level of overheating was happening even before the rebore as well.

The signs of black residue over the plug are seen - but I guess this is not the only evidence for the rich mixture (may be incorrect ignition timing is causing this).
I shall time the bike anyway. But basically I wanted to start/experimenting bit by bit - so that I know what was wrong and how was it rectified.

As mentioned in my precisou posts, I have set all the carburation parameters to stock condition which shall not lead the mixture to be lean (including the air screw to 1.75 turns out)

The only thing which was worrying me was the lenght of the air screw - as it was not reaching/closing the air hole.
I measured up the air screw last night and the precise lenght is 20 mm in all my carbs.

Just wondering what's the principle of leaning/richning the mixture when the air screw is hardly reaching the air hole

Re: is an engine overhaul necessary??

Tight clearance of the rings can also lead to overheating of the engine, now you may have to look at the rebore too. Don't wide open the throttle as it can lead to a seizure of the piston. Give it time to settle to the correct clearance.

What the company recommends for the stock set up is 2.5 turns out plus or minus .5 I think. So now you maybe running slightly rich. The carb air screw is very sensitive to even small turns.


I haven't dismantled a carb till now so I can't comment on this. But I think this is normal.
A carb works by Venturi effect as far as I know. Due to the draft that is passing through the carb, fuel too is drawn into it and mixed.
I think the air screw regulates the pilot


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Re: Random Questions regarding the RX series

Okk as per the engine overheating is concerened. Check the air screw turns. As rxdude says it needs to be 2.5 turns out, thats stock config. Run and then chek the spark plug reading. Everytime one plays with the screws check the spark plug color. Secondly this 2.5 turns screw method is very theoritical usually mechanics use as a quick tip of trade. Actual proceedure goes by listening the exhaust engine note and caliberating the idle and air screws. Change the air screw it will solve that potrusion youre concerned for.

Overheating can be the by product of dissconecting the lube pump too. Make sure you didnt disconnected the oil pipe which goes into the carb from the right side. Coz if its open it will pull in more air by suction thus leaning the whole a/f and running kean and hot. So if its open close it. Also your a/f gets disturbed by the oil in tank (mist lubrication) method. Because the oil supplied by pump in d carb is after the jet and venturi assembly whereas in mist lubrication system the a/f mixture ratio is in actual a/f+oil mixture. So the jets set to supply a particular a/f mixture dont really supply dat coz a little part of the Fuel (F in A/F) is taken by the oil thus oil sticks for lubing and what reaches to engine is lean mixture And may cause overheat.

Re: is an engine overhaul necessary??

could u let me know where is it in chennai........ i've asked few of my friends they have no idea either.

Re: Random Questions regarding the RX series

Thanks for the suggestion Ankitvile.

Few weeks back I did try setting the air screw to 2.5 turns very precisely with the watch count and also listening to the variation on revs and exhaust note by turning the air screw out with a very fine turns. This setting was on average setting (not too lean and not too rich) . The plug readings - blackish oily greasy residue

After to this I was monitoring the Transmission oil level for any drop. Suspecting the Transmission oil escaping into the bore. But the transmission oil level was healthy and was not dropping down even after 1500 kms.

Later I swtiched to premix and removed the oil pump from case. I made sure that the oil tube to carb is blanked properly. And also checked the revs for engine breathing any extra air.
This time the air screw set to 1.75 out (towards much richer setting)
Following this few hundred kms of run and the Plug reading - Blacking oily greay residue.

I completely agree that the autolube is always good as it provides the required amount of oil as per the throttle demand and also at a very optimum location in the engine intake, but here more or less I am trying to experiment few factors as I am in the process of eliminating this overheat issue.


In the mean time I checked the air screw length and it reads precise 20 mm.

This will still be a mistery if I change the air screw - as I still do not know if the air screw is of correct lenght, If it is an correct one then what length air screw should be installed ?

Yamaha RX 135 5Speed - Scare about Engine cese if go Long drive

Hi,

Last year, I bought Yahama RX-135 5 Speed (2000 Model) with good condition. After I bought, I did not go long drive. I am using upto only 15 km- 20km max. If I go long drive like 100km with speed of 90-100km per hour without stoping anywhere. With proper Oil.
Will that engine cese(stuck)?

One of my friend scared me about that...

Pls adivce me that bike will help to go long without getting any troble?

Thanks
R. Eswaran

Re: Yamaha RX 135 5Speed - Scare about Engine cese if go Long drive

Query Approved and Merged

Re: Yamaha RX 135 5Speed - Scare about Engine cese if go Long drive

What is the condition of your bike. Yours is one of the best RX model from Yamaha which has the highest top speed. If your bike is in good condition(that includes brakes too) there is no problem at all.
For long rides as a safety measure add a little 2T oil in the tank too. That is what most of the RX owners do.
Its best that you speed up gradually till the engine temperature reach the optimum level. That is don't try to rip a cold engine as it reduces the engine life.
RX is best to be ridden at 70-80KMPH. Who ever is your friend is misleading you.

Read this and this for clarification of your doubts..

Re: Random Questions regarding the RX series

[QUOTE=augmentor;962898]The plug readings - blackish oily greasy residue./QUOTE]
That shouldnt be happening. Still its so? And yaar carb is the only thing which needs to be fabricated or tuned to solve this issue. At last you can get another carb. Consulted a mechanic yet?? And also if its really overheating....i mean everyone has different thresholds after which they think engine is overheating !!....Anyways dats what im thinking. Baaki do update on any progress.

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Well guys have been on it to ladakh. Its used in rallys etc. Nothing will happen. Just constant 90-100kph is too much. Be on the safe side ride the way Rxdude says 70-80 is great.
And an advice (rule of thumb riding a two stroke for me) ...Dont ride on a constant throttle position for a long time. Keep it varying. It will keep piston operating temperatures down and block away from siezure.

cylinder compression of yamaha rx-100

Hello guys i have an 1994 yamaha rx-100(pics attached), a few months earlier u guys helped me in getting luggage carrier for my bike so iam here again to get some help,my bike is running on second o/s piston , previously the compression of cylinder used to hover around 150-155 psi mark, but recently the compression has gone down to 140 mark though there is no weird sound from the engine right now she is sounding same as she was sounding when the pressure was 150 psi, but still i wanna know that should i change the piston rings infact i have just purchased second no goetze piston rings and was thinking of replacing them but before i change them i want the opinion from u guys ,also i want to know what is the compression of an healthy engine, how much of play in the crank assembly is acceptable,i hope this thread will be approved and you will reply soon.

Re: cylinder compression of yamaha rx-100

you can replace the rings if its still within the piston clearance. If its more then you have to rebore it. RX100 has 4 OS i think(not sure). But 140PSI is fine

For 135 the free play is .03 to .18. there shouldn't be much difference for a 100. the manual says anything more than that is unacceptable

Re: Random Questions regarding the RX series

[MENTION=49419]kusmaker[/MENTION].Is it 12volt or 6Volt one?

Yamaha RX100 issues

Hello Everyone!

I am having a few issues with my Yamaha RX100 which I bought 2 years ago.

1. The clutch has run so smooth that it is difficult to engage gears now.
I opened up the screw near the clutch lever so as to tighten the wire , it helped but its the same after a weeks time!

2. The rear drum is making some sort of a noise , maybe its the bearing. I removed the rear brake and found that the brake shaft was not aligned and had serious play.

I do not know whether to change the clutch wire or is it some other problem?
And also, what about the rear drum?
Suggestions are welcome

Thank you !