65cc motor kit over heating ?

Is it normal for a 50cc moped motor, newly refitted with a 65cc kit to run alittle hot before the break-in period is over ? Mine gets real hot on the hills now and will begin to sieze if not kept at half-throttle. I'm hoping that alittle extra oil and running only half-throttle during the break-in period will allow the clearances to loosen up a bit and make less internal heat.

Also, a shorter spark plug was put in the motor after the 65cc refit but now it is a bitch to start when the motor's cold....maybe it's too short and I should try the old sparkplug ?

Jimmy

Re: 65cc motor kit over heating ?

Jimmy,you didn't say what kind of bike it is.Make sure the engine's clean and you don't have a brake dragging or anything.Yes,they'll run hot I understand.Make sure your timing's not too fast.That make's for heat also.I don't know about the plug length,but a cooler plug in the original type would be what I'd try.You may want to go to a quality synthetic 2-cycle oil since you've nearly seized it.But stay with a 40:1 ratio if you use what I use:Pennzoil Marine synthetic 2-cycle oil at Wal-Mart.

Re: 65cc motor kit over heating ?

Listen to Don , plus a new cylinder/piston could take from 100 to 600 miles to break in so do it at half throttle and by all means do not put hi test gas in it ,,, it burns hotter and breaks down the oil worse so it will do more harm than good!! Rog

Re: 65cc motor kit over heating ?

Ron Brown /

Jimmy,

Do a plug chop now, while you still have a piston and cylinder.

Don and Rog gave good advice but if your mixture is lean, you are in big trouble.

See Fred's How to fix your moped in resources, articles for plug chop instructions.

Ron

Re: 65cc motor kit over heating ?

Yeah,Ron.Good advice.I didn't think he was lean because of the hard cold starting,but it's a possibility.Those kits do need a big jet.And richening the oil mixture actually leans the set-up.

Re: 65cc motor kit over heating ?

Ron Brown /

Don,

You want to read your post again and tell me why you need a choke to start a cold engine? : )

Ron

don-ohio wrote:

>

> Yeah,Ron.Good advice.I didn't think he was lean because of

> the hard cold starting,but it's a possibility.Those kits do

> need a big jet.And richening the oil mixture actually leans

> the set-up.

Re: 65cc motor kit over heating ?

Ron Brown /

Jimmy,

I'm confused by the shorter plug. Is the threaded portion shorter, and if so, did you replace the head? The plug threads should be the same length as the thread depth in the head, is tis true of yours?

Ron

Re: 65cc motor kit over heating ?

Duh! Right,Ron! I had that backwards.I think...............

Re: 65cc motor kit over heating ?

Thanks for answering, guys... what I meant by a shorter plug is that he changed my plug from an NGK B7HS to a B6HS, I believe it is.. it's a colder plug, the metal arm coming off the bottom of the plug is shorter....I have to really peddle my bike like hell now to get it running from a cold start..but once it warms up for even a minute it can restart very easily.He did that because I think he was worried about the new larger piston hitting the bottom of the plug, so he opted for the B6HS with the shorter metal arm..

I had this mod done to my Avanti moped....so far gets about 5 mph increase in speed...If it loosens up and lets me run at full throttle without overheating it will be a great moped to keep up with traffic ..I think everything is tight yet because she gets real hot when I go up-hills. I've driven about 90 miles and it may be starting to loosen up a bit...But it's frustrating having to run at half-throttle, ain't it ?? !! Still, at half throttle she's doing about 25mph so it's not like I'm dragging too bad...my old Puch only does about 24mph full throttle :)

I'm still using the old carb,I won't opt for a larger carb until this motor proves to me that a break-in period will let run at normal temperatures.

I was just hoping that I might hear from others who have had a similar piston kit put in and that maybe they had to run theirs at half-throttle for a few hundred miles also before their motor loosened up and ran at normal temp ?

Jimmy

A 6 is hotter.. not colder

and between the new parts and possibly lean jetting and a hotter plug... you heading to a major seizure... so the money you spent on a new piston could be toast.

Put the 7 back in and turn the motor over slowly and see if it hits... I highly doubt it.

Re: A 6 is hotter.. not colder

Thanks Fred... if the B6hs he put in there creates more heat,then I am going to try the older B7plug in there to see if it reduces the heat any..... I don't think it'll become toast though.....I only run at half throttle and am not allowing it to over heat too bad....

DO A PLUG CHOP!

Ron Brown /

Jimmy,

All of the sugestions here are good...but if you do not do a plug chop and check your mixture, you are not understanding the potential for disaster.

Ron

Re: 65cc motor kit over heating ?

Ok, I did a plug chop and everything looks good....well, I've found out what caused the over-heating ....the dude that put in my cylinder had changed my plug too...he put a hotter plug in and the sucker was over-taxing my motor !... he kept my old plug, a champion plug that I can't find in my area, so I couldn't put my old plug back in to try it...... on the way home today I stopped at the auto parts store and found an NGK B7HS, a colder plug ( thanks Fred for making me clear on that! )

And today my ped ran awesome..man, what a big difference a plug can make.... I rode 35mph with no over-heating, and for giggles goosed it up to 40mph a few times....downhill she wanted to climb to 50mph , I got nervous and just backed way down to 35mph again....yeah, the colder plug was exactly what I needed...this is plenty fast enough now for me to make my 30 mile work commute every day....guess I won't need a scooter afterall :)

Re: 65cc motor kit over heating ?

Ron Brown /

Jimmy,

Good for you, swarm and destroy!

Eon

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