Engine modifications at new engine or after run in?

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GPXRacer

New Member
Oct 2, 2010
20
0
0
Los Angeles, CA
Hello,

I should receive my kit tomorrow (80cc Class (66cc True Displacement) Silver Slant Limited Edition Bicycle Engine (Model: ZB-80S-SR)).

I will build it in my MB which has for sure not the best tires to reach high speed... I want to do some modifications to the setup and the engine to get this bike up to 35-40mph. Can I do this immediately or should I wait until the engine is run in. I will do the modifications step by step but I want to run in the engine in a good way.

E.g. I would like to know if the 36t sprocket will hurt during the run in as the engine wouldn't reach high rpm's anymore.
How about a performance air filter, the two holes in the carb etc.? Do I have to wait until the engine is broken in?

I did a lot of stuff on my cars and motorbikes before but have no experience with 2 stroke engines...

Can't wait to get my toy....

scratg
 

GPXRacer

New Member
Oct 2, 2010
20
0
0
Los Angeles, CA
The 44t sprocket comes with my kit, I haven't ordered the 36t sprocket yet. I want higher max speed with lower rpm. I found lots of treads about this, outcome for me was a 36t sprocket which requires some more muscle work for the start but relaxed cruising around 35mph.
 

gubba

New Member
Dec 29, 2008
149
0
0
jacksonville, florida
have built over 25 china girls and those getting a 36 tooth have experienced about an 8 mph increase.
here in florida if you go over 25mph you get a $100 ticket.

also........ a good friend went over the handlebars at 20mpg and put 5 days in the hospital with 5 broken ribs, a punctured lung, broken sholder and collor bones and 12 staples in his head....... at 20mpg....


stay dry
gubba
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
Not trying to be a wet blanket here but if I may, could I suggest you spend a little time and money on your bike before going for performance. Brakes, tires and frame integrity should be your first priorities; then go for speed. You've already admitted that your tires are questionable, maybe take a look at the other things mentioned. Have fun but please, ride safe.
Tom
 

GPXRacer

New Member
Oct 2, 2010
20
0
0
Los Angeles, CA
The brakes are hydraulic (Magura) brakes. It's a good MTB with front suspension etc. The tires are not the best for high speed because of the high resistance caused by the offroad profile.
I know how it feels like to take off at these speeds, had some motorbike and downhill-MTB accidents at even higher speeds.
.duh.
I wear the right helmet and protection jacket.

Does somebody know how much is the ticket in L.A. if you get stopped over 30mph? I want to keep up with the traffic not to get overtaken the whole time as this can be dangerous...
 

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