1974 Honda XL 250 Motosport

[Riddell]

Hi Folks, I'm new to this site and this is my first post, and I am enquiring whether there is someone out there that has experience with the current fuel and carburation settings for my bike. I've been told that i should be running it leaner with a hotter plug to stop plug fouling. Any ideas appreciated? I have lowered the needle to the lowest position and at the moment it seems OK , but just wondering if others have found a solution without running it on 100 octane?
Thanks

[Brian d marge]

Hi Folks, I'm new to this site and this is my first post, and I am enquiring whether there is someone out there that has experience with the current fuel and carburation settings for my bike. I've been told that i should be running it leaner with a hotter plug to stop plug fouling. Any ideas appreciated? I have lowered the needle to the lowest position and at the moment it seems OK , but just wondering if others have found a solution without running it on 100 octane?
Thanks

1st thing first , make sure everything else is ok

are the needle and seat , ok? not flooding? blocked aircleaner ?

Stephen

[Paul in NZ]

All our old bikes have fouled plugs at low engine speed on unleaded fuel. The triumphs being the worst and you can't lean it much as its the pilot jet (non adjustable) thats the main player at low throttle opening. I run an extended tip 1 grade hotter plug and everything is sweet. The dellortos on the guzzi have more fiddle factor and you can tune it out but its still too rich - work in progress...

[Brian d marge]

Dont go blaming the fuel , it is different but has similar burn characteristic .

as does summer and winter fuel ,

But as Paul said a little bit of a fiddle is ok , but if your dropping needles to lowest position , step back and have a rethink ,
1 plug grade either way isn’t going to make much of a difference


post your settings , and a description of plug color

Stephen

[Paul in NZ]

Beside - isnt the XL a 4 V pent roof head? It should be efficient enough to work OK as opposed to my shitty old 2 valvers.

My problem was not the mixture but that the plug was not getting hot enough to self clean....

[F5 Dave]

Hi Folks, I'm new to this site and this is my first post, and I am enquiring whether there is someone out there that has experience with the current fuel and carburation settings for my bike. I've been told that i should be running it leaner with a hotter plug to stop plug fouling. Any ideas appreciated? I have lowered the needle to the lowest position and at the moment it seems OK , but just wondering if others have found a solution without running it on 100 octane?
Thanks
Hi

So have you been having problems fouling plugs, or is it just a response to someone telling you should be doing something?

Going leaner is never a good policy unless it is too rich. Remember that the needle only affects a range of throttle positions from about between 1/4 to 3/4 open. It could be lean or rich at either extreme & this won't alter it there.

Hotter sparkplug is just a cop out, try running std before resorting to this bodge.

Presumably the lovely old exhaust is long gone? Freer flowing tend to run leaner esp at higher throttle, but not always. What is the airfilter like? Bodged replacement? New original? Scummy old one?
How is the coil/lead/cap?
Also take the carb out & check the float jet seals & oggle the needle jet (that the needle slides in). These can wear oval, even slightly will affect running & foul plugs. You will need a strong torch & a keen eye.

[Paul in NZ]

Hotter sparkplug is just a cop out, try running std before resorting to this bodge. zz.

Hardly a bodge in my case dave - 3 different std carbs tried, 3 different ignition systems, bike is a std as it can be and considerable contact with fuel companies, plug makers and other triumph owners globally. Eventually there were 2 options - one was beyond me engineering wise and may have fucked up a $200 carb body and the other was a change of plug.

It works and has worked for a very long ttime

[F5 Dave]

Hey I ran a hotter plug in my trail ridden Enduro bike, but typically a Japanese bike will have close to the right plug in it, ok they may go for the safe option, but I'm just saying leave this as a last option rather than attack a symptom.

[koba]

I've been told that i should be running it leaner with a hotter plug to stop plug fouling.

Always be very careful about advice like this.

It may be well informed and perfectly correct but often general 'wisdom' takes over and things can be distorted or just plain wrong.
I've wasted a fair bit of time over the years chasing shit that was just 'wisdom'.

Do you actually have a problem with the bike or does it run fine?

[Riddell]

I have restored this bike and the carb. Put a carb kit through it, all new and all standard parts. I set the float level according to the manual, new air cleaner, plug, points. Put everything back to what I thought would be a standard, 1974 starting point. Bike would start well and run well. After a couple of weeks of mostly short running trips, it would progressively get hard to start. I would take out the plug and it would be black and sooty, as the exhaust pipe. After plug cleaning, all would be fine again for another couple of weeks and then the pattern would start again. It seemed to be too rich, so after some advise, I lowered the needle one slot and put in an hotter running plug. Basically the same cycle started over with the plug still black and sooty. I have now lowered the needle another notch to the lowest position, and it seems to be better at the moment with the plug a more fawn color. Some people have advised me to run it on 100 octane, others to lower the float 1mm, while others say those old 4 stroke engines used to run fine on anything. I guess for now as it seems to start good and plug colour is good, I should leave it as is.But it has certainly been quite a bit of adjusting and to me, it seems hit and miss. Regards

[Brian d marge]

Battery holding a charge , charging system ok ?

Stephen