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warrenpeas 12-17-2023 10:07 PM
250cc 4 valve Grom Clone
 
2 Attachment(s)
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.

delzy 01-19-2024 11:51 PM
Nice project. 90 on a mini! WOOT, WOOT!! I just picked up one of these recently and I'm almost done building it into a stunt bike. I'm sticking with the 150, but I replaced the carb with a tunable PZ27 and the exhaust with a KPT200 pipe and a slip-on muffler.



I just joined up so I'll probably document my build. I'm coming out at a total around $2500 total. Can you tell me more about that exhaust you have?

warrenpeas 01-20-2024 06:32 PM
exhaust
 
the pipe is from aliexpress listed as kpt200 exhaust. the slip on is from amazon. https://www.aliexpress.us/item/32568...Cquery_from%3A

Bruces 01-20-2024 06:54 PM
What’s up with the engine ?the name on the side of it looks like zonsen ,is it a clone of a clone or are my eyes failing me faster than I think ?
I have no interest in these bikes but it would be a lot of fun wringing it out .

Thumper 01-20-2024 08:14 PM
4 valves ?!
 
Nice swap! but Whoa,whoa, whoa. That is a 2 valve engine, isn't it?

4 valve zongshens are WATER cooled, aren't they?

warrenpeas 01-21-2024 02:57 AM
Quote:
Originally Posted by Bruces (Post 403795)
What’s up with the engine ?the name on the side of it looks like zonsen ,is it a clone of a clone or are my eyes failing me faster than I think ?
I have no interest in these bikes but it would be a lot of fun wringing it out .
Zongshen is the name of the founder i guess they have changed their name to Zonsen Industrial Group Co., Ltd https://en.zonsen.cn/. I dont know whay they put Zonshen vs Zongshen on the side but i know if you order more than 10 i think the number is they will put whatever you want on the clutch cover.

warrenpeas 01-21-2024 03:10 AM
Quote:
Originally Posted by Thumper (Post 403798)
Nice swap! but Whoa,whoa, whoa. That is a 2 valve engine, isn't it?

4 valve zongshens are WATER cooled.
no its 4 valves. rated t 23.4hp but i guess 19.5 at the wheel on the dyno according the the russian video below.?

turn on closed caption and change the setting to english to understand what the hell they are saying.

here is the video of the 4v head https://www.youtube.com/watch?v=zazakTXrAFw

here he disassembles the top end. https://www.youtube.com/watch?v=ygNu07IzJSc

here is the video of the dyno test vs the zs172fmm-6 vs a 172 2 valve i think and explain the power band difference https://youtu.be/64LZdA7TjEM?si=A0C98RyYl6hb4s6r&t=1862.

here he compares the zs172fmm-6 to an older 2 valve version? zs172fmm-? https://www.youtube.com/watch?v=JBeUd-BnGPE

i just found these videos earlier today before work and havnt had time to watch them all and read everything they said but it is informative.

warrenpeas 01-21-2024 03:15 AM
Quote:
Originally Posted by Thumper (Post 403798)
Nice swap! but Whoa,whoa, whoa. That is a 2 valve engine, isn't it?

4 valve zongshens are WATER cooled.
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.

Thumper 01-21-2024 07:05 AM
1 Attachment(s)
Amazing! Very cool. I like it !!!

I FOUND it. Yes, the ones I found appear to be 5 speed. I see the gear position diagram has 1-N-2-3-4-5 in the decal on the stator cover:

Attachment 30695

I saw "Zongshen" on one red valve cover photo. I wonder if Zonsen is another pirated logo, or just a different Zongshen logo. Could be made by Zongshen.

Heat could be an issue depending on where you are driving and how hot it is out. You would want wings focusing air through that head if you are riding off road (slower speeds, more work!).

warrenpeas 01-21-2024 12:20 PM
Quote:
Originally Posted by Thumper (Post 403811)
Amazing! Very cool. I like it !!!

I FOUND it. Yes, the ones I found appear to be 5 speed. I see the gear position diagram has 1-N-2-3-4-5 in the decal on the stator cover:

Attachment 30695

I saw "Zongshen" on one red valve cover photo. I wonder if Zonsen is another pirated logo, or just a different Zongshen logo. Could be made by Zongshen.

Heat could be an issue depending on where you are driving and how hot it is out. You would want wings focusing air through that head if you are riding off road (slower speeds, more work!).
im using an oil cooler. the oil going in is at 145F and out at around 205F after 20 minutes idle. im adding an oil temp gauge soon. what should the operating temp be?

warrenpeas 01-21-2024 12:46 PM
1 Attachment(s)
this guy says the engine can have overheating issues so he added ports to the head cover for his oil cooler. He is using the motor in a dirt bike im using it in a street bike.

warrenpeas 01-21-2024 02:45 PM
now there is a 300cc version with the 4 valve head and counterbalance ZS175FMN with 6 speeds. actually according to the bore and stroke calculator it is only 271cc

warrenpeas 02-03-2024 06:07 PM
Quote:
Originally Posted by Thumper (Post 403811)
Amazing! Very cool. I like it !!!

I FOUND it. Yes, the ones I found appear to be 5 speed. I see the gear position diagram has 1-N-2-3-4-5 in the decal on the stator cover:

Attachment 30695

I saw "Zongshen" on one red valve cover photo. I wonder if Zonsen is another pirated logo, or just a different Zongshen logo. Could be made by Zongshen.

Heat could be an issue depending on where you are driving and how hot it is out. You would want wings focusing air through that head if you are riding off road (slower speeds, more work!).
my motor literally has this decal on it i dunno what i was thinking.

Thumper 02-03-2024 10:51 PM
You have a rare engine there, and fitting it into the Grom clone must have taken some deft engineering. Very cool.

warrenpeas 02-04-2024 09:23 PM
Quote:
Originally Posted by Thumper (Post 404165)
You have a rare engine there, and fitting it into the Grom clone must have taken some deft engineering. Very cool.
it actually bolts right in the rps condor 150 because it already uses a cg150 upright engine.

BJ 02-05-2024 08:38 PM
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 02-06-2024 07:59 PM
Quote:
Originally Posted by BJ (Post 404227)
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 02-06-2024 08:53 PM
Quote:
Originally Posted by warrenpeas (Post 402773)
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 02-07-2024 07:03 PM
pictures
 
4 Attachment(s)
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 02-07-2024 07:48 PM
That is one seriously musclebound Grom clone.

It looks gnarly, probably rides that way too :)

Nice

warrenpeas 02-07-2024 08:20 PM
Quote:
Originally Posted by Thumper (Post 404289)
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 03-27-2024 03:07 PM
How the progress?

delzy 03-30-2024 12:05 AM
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 03-30-2024 10:58 AM
Quote:
Originally Posted by warrenpeas (Post 404287)
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 03-31-2024 02:13 PM
Quote:
Originally Posted by warrenpeas (Post 403809)
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 03-31-2024 02:23 PM
Quote:
Originally Posted by warrenpeas (Post 404290)
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.

ProDigit 05-15-2024 11:18 AM
I doubt a 300 will fit, but it might. Some YouTuber put a CBR300R engine on a Grom. So you never know.
Personally, I think the Sweet spot is between 175cc and 200cc.
You still get good fuel economy, especially if it's a higher compression engine, tuned well, but also a lot more torque and top speed than the 150.


I'm wondering if it was a plug and play, or did you need to weld any mounts?
From the space I see inside that bike, I probably would want a size smaller engine.

Quote:
Originally Posted by warrenpeas (Post 403816)
... what should the operating temp be?
Most engines run between 180 and 212F, this due to them being water cooled and 212F is the boiling Temperature of water.


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