250cc 4 valve Grom Clone

[BJ]

Where did everyone order their engines from? I see plenty of Cg250's on ebay and Amazon and Xpro Amazon sells a CR250. The only place I see alot of other options are the A1j website.

[warrenpeas]

Originally Posted by BJ

Where did everyone order their engines from? I see plenty of Cg250's on ebay and Amazon and Xpro Amazon sells a CR250. The only place I see alot of other options are the A1j website.

i buy mine from alibaba. have bought 4 in the past 18 months. look for the seller CQJB they are completely professional and located on chongqing very close to the zongshen factory. they do live streams on alibaba. they will get you what you paid for on time. we have bought over a dozen engines from them and never a problem. you can ship via air for 10-14 day delivery to usa or via sea for 30-60 day deliver and save a few bucks. @Anna Hu is on facebook and is the CQJB seller we use. also alibaba has buyer protections where they dont get paid until you inspect the product and accept delivery.

[Thumper]

Originally Posted by warrenpeas

Hi im in the south Kansas City area

This is a Condor 150cc swapped to the Zongshen "CB250r" 250cc 4 valve engine. Complete build price after i insall the wideband AFR gauge and the new cluster is about $2800 but i sold the 150 motor brand new for 400$. The idea was to create something more reliable and less expensive than the Daytona/zongshen 212cc 4 valve. This motor cost me $560 and i know the ZS212cc 4v is around $1100.

https://www.youtube.com/shorts/DFqqaxOrgqE

I will be happy if it can hit 90mph with the 17/31 sprocket setup.

Can you post a few close up photos of the mounting of this 4 valve 250 in the Grom clone?

I still can't believe it. I mean photos showing the head in that frame!

Thanks!

[warrenpeas]

its only a tight fit for the throttle cable on the pwk32 carb. only about 1/2 inch space between the throttle cable and the tank.

you see that blue hose connecting the carb to the manifold? im going to try a piece of 1.5 inch diameter pipe instead of this silicone blue hose to connect it to the manifold i think because i can feel that hose slightly collapsing and expanding when the engine is running. the frame is in the way so that 3 inch section of hose is needed to move the carb back close to the rear tire to clear the frame . im talking about the side setion if the frame being in the way because that manifold angles to the right and i cant find a better manifold one because it needs to be oval not circle to match intake port on the motor.

[Thumper]

That is one seriously musclebound Grom clone.

It looks gnarly, probably rides that way too

Nice

[warrenpeas]

Originally Posted by Thumper

That is one seriously musclebound Grom clone.

It looks gnarly, probably rides that way too

Nice

im having difficulty getting it tuned. first i tried a 28mm PE carb i think is too small and my wideband gauge was telling me the main jet needed to be 100 or 105 which i cant understand at all so today i put on the 32mm pwk and im getting closer with a 130 main jet

[MeToo]

How the progress?

[delzy]

I'm going to do this to my RPS Condor, but I think I'm going to use a 2 valve engine for 19HP. Updates?

[Thumper]

Originally Posted by warrenpeas

its only a tight fit for the throttle cable on the pwk32 carb. only about 1/2 inch space between the throttle cable and the tank.

you see that blue hose connecting the carb to the manifold? im going to try a piece of 1.5 inch diameter pipe instead of this silicone blue hose to connect it to the manifold i think because i can feel that hose slightly collapsing and expanding when the engine is running. the frame is in the way so that 3 inch section of hose is needed to move the carb back close to the rear tire to clear the frame . im talking about the side section if the frame being in the way because that manifold angles to the right and i cant find a better manifold one because it needs to be oval not circle to match intake port on the motor.

It is amazing that you squeezed it all in there. I see no upper engine mount. Can you fabricate one to the stays (or even from one stay) coming down beind the cylinder?

And you managed to get oil cooler/lines in there too. Wow.

[delzy]

Originally Posted by warrenpeas

when i was looking for ths motor i was tlaking to a seller in China i had bought zs190 horizontal engines from. i told him i wanted the most powerful Vertical AIR COOLED 4 stroke engine he could sell me and this was it he told me. although i wonder if there might be a more powerful 300cc option after looking into it more. Oh and i was trying to keep the price under 1000$ delivered. I paid $560 for this delivered to my door. in comparison the zongshen 212cc 4 stroke horizontal motor is $1080 delivered.

OK, I just pulled the trigger on the 4-valve 250. There is also a 4 valve 300, but it appears to have a funny exhaust angle, so I thought 23hp would be enough. The 300 is the
Zongshen NB300-F

Someone should try this out.

[delzy]

Originally Posted by warrenpeas

im having difficulty getting it tuned. first i tried a 28mm PE carb i think is too small and my wideband gauge was telling me the main jet needed to be 100 or 105 which i cant understand at all so today i put on the 32mm pwk and im getting closer with a 130 main jet

I think when you go down on carb size, you also have to go down on jet size because the smaller throat and higher flow results in a much more powerful venturi. I'm planning on using my pz27 on it. I would love the wide band. It is telling you you're rich when it said to bring the jet size smaller.

This makes sense when you think about it because the airflow is increasing while the throat isn't so you get a bigger change in pressure. Now I need an oil cooler. I ordered a 30 tooth 520 JT rear sprocket for a grom that I hope will work. I don't think there is room for a 16 or 17 up front. I'm also going to get creative to get that intake right.