Honda urban express overheating

Hey y’all I’ve been plagued with overheating issues, destroyed 2 70cc kits, and the stock head. I’m planning on buying another 70cc kit but I’d like it to not blow up. I use pre mix, have the vm18 carb, mlm peoples side bleed pipe. Any ideas? TIA

Re: Honda urban express overheating

Hepatitis J [OFMC] /

It's probably your jetting or an airleak. Why are you buying a third cylinder? how fucked are the first two you blew up?

Re: Honda urban express overheating

Scored, why do you think I just get one honed?

And air leak where?

Re: Honda urban express overheating

Hepatitis J [OFMC] /

Yeah you should definitely try to salvage the cylinders and just get a replacement piston. Get a brake cylinder home for like $12 and try cleaning up a cylinder. An air leak would probably give you other warning signs before blowing your bike up. Did it otherwise run and idle okay before blowing up?

Also, just get a temp sensor and use it while tuning or breaking in a build.

Re: Honda urban express overheating

Yeah it ran okay as far as I can remember, what should the premix ratio be around? I do 40:1 and I feel like that’s not enough and could contribute

Re: Honda urban express overheating

Hepatitis J [OFMC] /

I'm getting the sense you didn't jet your bike at all and just threw the vm18 on and ran it.

Re: Honda urban express overheating

Jack Rutherford /

Get a temp gauge, puchHonda head, replace crank seals, bigger main jet and run the Honda aero cdi.

Re: Honda urban express overheating

No I bought more jets from 65-75

Re: Honda urban express overheating

Hepatitis J [OFMC] /

Those jets are definitely too small for your setup but don't just go guessing. Read the wiki, tune your carb, buy a temp gauge, stop blowing up kits. You can do it, it's easy.

Re: Honda urban express overheating

What would stock cylinder run around for jet size?

Re: Honda urban express overheating

I had a DR with I think a 78 jet. Also, what's your oil mix? Are you running the stock oil injector? I wouldnt (I did once, it cost me a kit)

Re: Honda urban express overheating

Running 40:1 mix I believe

Re: Honda urban express overheating

Captain Janeway /

Temp gauge, look for air leaks ( you should probably change the crank seals). I didn't change the CDI but I'll go with Jack if that it helps. Don't run a VM so don't know the jet sizes but if you're overheating and you're sure you don't have air leaks, jetting is a good bet. I'd rather have them bigger to the point of 4 stroke and work down.

I run a kit with stock head, stock carb with about a 98 jet, light weights, BX31 belt (I'll change to an AX later), Weakends pipe. It goes over 40 mph

Re: Honda urban express overheating

Jack Rutherford /

Stock cylinder with performance pipe will run near 70 main jet. I’ve got a 67.5 in mine now. I’ve forgotten what I ran with the dr kit. Maybe 77.5-80 main jet. Try that Honda aero cdi. It will really bring down temps.

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