Advice on using choke to stop heat seize on long ride

[nastro azzurro]

If i'm on a motorway and cruising for any length of time at high speed I always roll the throttle on and off so as to flood the engine with more fuel therefore aiding cooling.
Not blown up my engine yet after 5 - 6000 miles !
I also ride covering the clutch even though its a nicasil lined barrel. I think its to do with being brought up on a cast iron 240 conversion way back in the mists of time !!!

[rbgaz]

in my exp rbs even when jetted ok will after holding the throttle at revs over 6 k for long periods start to slowly rise the heat, so if the choke will cool it down a touch its worthwhile imo and will do no harm, as for other kits i hav no idea

[Adam_Winstone]

I have used the choke on, as a get me back home trick, when my scooter had shown the signs of a heat seize, in order to prevent being stuck in the middle of nowhere.
The problem I then had was sorted out, (spilt carb rubber) and the jetting was returned to normal.

If someone is using the choke on, in normal practise, the carb/timing needs sorting out or they have no faith their scooter!
Having said that I always ride with my hand resting on the clutch lever.....just in case!

Cheers Rick.

^... I agree with the above.

[tarmac tickler]

I have a thumb operated choke that I bought from Mr Taylor and since have used an old gear change lever to do the same on the sprinter, I have a trail tech temperature sensor that's sits under the plug, and thought my jetting was perfect till I went to scarborough at the weekend, got a leanspot at 55mph when the temp went to 100 c.. Quick press went back down below 80 c. Normally sits at 85c, I wouldn't be without one now, don't know how I managed before,

Also found it runs cooler now I use denso spark plugs,,ngk shite

[Darrell Taylor]

I have a thumb operated choke that I bought from Mr Taylor and since have used an old gear change lever to do the same on the sprinter, I have a trail tech temperature sensor that's sits under the plug, and thought my jetting was perfect till I went to scarborough at the weekend, got a leanspot at 55mph when the temp went to 100 c.. Quick press went back down below 80 c. Normally sits at 85c, I wouldn't be without one now, don't know how I managed before,

Also found it runs cooler now I use denso spark plugs,,ngk shite

thats good info and something that is rarely considered on a scooter temperature

if you drove your car down the motorway and the temp gauge was sat in the safe green zone you would continue ,but if it went into the red you would take appropriate action or pay the price!

on a scooter which is air cooled with a poor cooling system and many performance upgrades which increases heat further
how do you know if your overheating your motor without a temp gauge,bad fuel/blocked jets/poor fuel flow/frothing fuel/kinked petrol pipes/over advanced timing /blocked exhausts/blowing gaskets /split rubbers/air leaks/low plug grades/lean jetting etc etc. or just nothing more than a heavily laboured motor getting hotter and hotter
a temp gauge to warn of an issue and a choke lever to cool it makes a great combo

[Stringy]

Which type of gauge would people recommend for a basic indication of an engines running temperature?

Cylinder head temperature or exhaust gas temperature?

Thanks

[nelson pk]

Regarding Egt and Cht. Use both to be belt and braces or go for a detonation sensor which by far is the best, although i must admit to just having egt at the moment. If your cht goes up considerably and your egt goes down or up considerably at the same time you know you have a problem.
The handlebar choke is a good idea to rectify an issue should it arise (air leak etc) as is an adjustable power jet. In my case i went for the power jet. Have it set up and your motor will be nicer to ride and if a problem arises you can just turn it up a bit more and when you have fixed the issue go back to your original settings.
In short though, if you dont have an issue and your bike has been jetted with touring in mind, in my opinion, you should not need the choke on. Of course this will cool the motor if you put the choke on but if its jetted correctly for long distances it will start to lose power unless its lean in the first place.

[Darrell Taylor]

i think straight head temp/under plug temp works very well

no magic numbers so ignore the numbers below
on a known good running motor
ride it round town and get a base line say 75 C
then open it up on a longer A road say 85C
then nail it and get say 95C
make a mental note or create a sticker and keep an eye out for abnormal running temps
if its showing 95 on a steady round town ride then something may be wrong
egt is a bit trickier to follow and more expensive but very good too

any temp measuring is better than none at all

any more info on typical cht or under plug temps seen

[Adam_Winstone]

I agree that a choke can be used to bring down temps, indeed, I do that if I feel a bike is running hot or weak, then I sort out the issue (e.g. correct my jetting or timing, dump rubbish fuel, etc). However, the point that I was trying to support is that choke operation to rectify a jetting problem would/should not be necessary on a correctly jetted road bike. Sure, a thumb choke can be used to good use on a 'special' or road bike that you are trying to run at the optimum but it should not be considered as anything but a temporary correction on a well set up road bike.

A good example of when it can be put to good use was when both Eden and I found our bikes were running hot/weak on the Spanish fuel that we were faced by during Euro Lambretta a few years back. We both found that our regular UK tourers were suffering pinking and heat increase at certain throttle positions, which they didn't suffer from here at home. We didn't learn of each other's similar issues and choke use until we met at a garage on our way back. My pinking was cured as soon as we returned to the UK and refilled. I am also aware that Train Driver on here suffered issues with his UK dyno'ed BIG RT motor but found that running with the choke on richened it up enough to get him home. Please note that this supports the thought that choke operation during running can be used to good effect but that it really shouldn't be be needed on a well set up road motor.

If you want to use with adjustable chokes to maintain optimum 'real time' mixture, allowing for changes in external temps, altitude gains, reduced temps/air pressures at night, etc. and have the gauges to indicate real time adjustment results then go for it but to suggest that running with the choke on is good for a touring motor cannot be correct, unless the regular settings are poor.

I run EGTs and I regularly use 'choke on' tests to test jetting set-ups or cruising with choke on to rectify problems... but this still doesn't justify having to use the choke to avoid issues on a regular use road motor.

Adam

[Muppet]

think dat was wot I was wus tryin t be gettin over in me idiots post earlier y can only put it rite usin choke ifin its wrong t start with or so clse t lean anything tips it over the edge,