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Post by ThaiGyro on Jun 3, 2020 8:53:35 GMT -5
What Zino said: that much compression...to me, means dirty exhaust system. If the top end and intake are all OEM, and good shape, your pooh system could be plugged.
Drag a rat through it...or chem clean it. I am a simply an old folker...diesel inside and thrash it like your little brother. Always drain through a rag or coffee filter, just for knowledge.
Some will say heat it up. I am NOT one of those. But, I am a good welder. (That's a hint)
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Post by harleyracer59 on Jun 3, 2020 15:16:59 GMT -5
I also break in this way. one extra step though. after the 15-20 minute idle run. I let it cool off then recheck the head bolts intake and exhaust bolt torque. case bolts too if I split cases. gaskets squish with heat cycles last thing you want is a vac leak
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Post by mrchilled85 on Jun 3, 2020 16:11:08 GMT -5
9300 rpms sounds lie good porting for a sport build . 191 psi that is strong do you have a cht to monitor temps for that high compression. The ride it like you stole it method is what i like also It is so much easier to explain to my wife . Just warm it up real good every day vary rpms and get on it from harder and harder over time . Now that I say it like that It sounds like what I wish for every night since I got married . nope tho im planing to get something to monitor the temps yep 9300 rpm with stock exhaust with cat and 4gm rollers ,naraku variator , 17mm carb , 82 main jet i used the same way to explain to my wife as starting her build in 2-3 weeks to
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Post by mrchilled85 on Jun 3, 2020 16:13:17 GMT -5
What Zino said: that much compression...to me, means dirty exhaust system. If the top end and intake are all OEM, and good shape, your pooh system could be plugged. Drag a rat through it...or chem clean it. I am a simply an old folker...diesel inside and thrash it like your little brother. Always drain through a rag or coffee filter, just for knowledge. Some will say heat it up. I am NOT one of those. But, I am a good welder. (That's a hint) na was stock exhaust with cat still so was blasting the cat to bits my reeds are oem aerox but after market inlet
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Post by proy on Jun 7, 2020 22:55:29 GMT -5
i have been using a naraku 70 kit for 2 days now on my bike just passed 68 miles now so started to open it up more and what can i tell you the standing start pull offs now takes off so good seems to make good power over all the rpm im still using a stock pipe and has reached 9300 rpm still with a bit more to go as for brakeing it in all i did was let it run for 15mins at idle ( well in my case just over idle as need bigger idle jet ) let it cool off then went for a 30 mile ride only running it upto half throttle but try not to keep the throttle in one place let it get upto speed then back off the throttle a bit then back on next ride i did was 30 miles again but this time upto 3/4 throttle off and on the throttle a lot and around town riding since that 60 miles brake in i have been ride it like you stole it done a compression test this morning and has a nice 191 psi im using the stock 50cc head on the kit tho Thanks for the feedback about the kit. I think I have made my decision on the naraku kit as my first bore for the motor.
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Post by Mr Dave on Oct 16, 2020 8:51:21 GMT -5
I just got a kit from racing planet,, put it on, and the piston edge at TDC sits 4mm below the top of the head deck.
At BDC the top edge of piston is 2.23mm below the exhaust port.
Wondered about the low piston to deck cleance but thought well running my 50cc head should make up for it. base gasket is .50mm with a .10mm head gasket I can only get 90psi with compression tester. Something is not right at all with this kit, and since it came from overseas, and I've installed it already, I'm pretty sure it's a $100 paper weight at this point. Unless I can find someone to mill 2mm off the top of the cyl.
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Post by aeroxbud on Oct 16, 2020 11:38:15 GMT -5
I just got a kit from racing planet,, put it on, and the piston edge at TDC sits 4mm below the top of the head deck. At BDC the top edge of piston is 2.23mm below the exhaust port. Wondered about the low piston to deck cleance but thought well running my 50cc head should make up for it. base gasket is .50mm with a .10mm head gasket I can only get 90psi with compression tester. Something is not right at all with this kit, and since it came from overseas, and I've installed it already, I'm pretty sure it's a $100 paper weight at this point. Unless I can find someone to mill 2mm off the top of the cyl. Without machining anything, your best option would be to just use copper spray instead of the gaskets. Still far from ideal. But worth a try.
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Post by Mr Dave on Oct 16, 2020 13:07:16 GMT -5
,,, somethings wrong with kit,,,, I think wrong piston. it shouldn't be that far off. It only ha 90 psi when assembled. I put stock kit back on,, and will do something else, for now. Sadly riding season is over here in Mid Michigan.
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Post by fugaziiv on Oct 16, 2020 14:12:36 GMT -5
,,, somethings wrong with kit,,,, I think wrong piston. it shouldn't be that far off. It only ha 90 psi when assembled. I put stock kit back on,, and will do something else, for now. Sadly riding season is over here in Mid Michigan. If you use your stock head (I didn't see if you were), this kit normally has some pretty stout compression. something is weird here. Matt
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Post by geoffh on Oct 16, 2020 14:12:58 GMT -5
Mrdave,just to confirm and explore I have a Naraku NK100.31 70cc kit waiting to go into action ,a quick mock up on my spare Yamaha engine did not look bad
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Post by geoffh on Oct 16, 2020 14:20:00 GMT -5
Mrdave,post continuation,both the exhaustport match up and tdc are very close to ideal to my eyes.just a guess but have you replaced the little end bearing with new Naraku one. Geoff
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Post by Zino on Oct 16, 2020 14:56:12 GMT -5
geoff that looks close to perfect lined u with transfers Something is not right with your kit mrdave
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Post by aeroxbud on Oct 16, 2020 15:47:32 GMT -5
That's way better than my Polini one Geoff.
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Post by morrislowe on Jan 12, 2021 13:20:26 GMT -5
I’ve recently put a 70cc naraku kit in my Yamaha bws ng with original head
Doesn’t want to start up when I kick the engine Is there a chance would need to use a different thread spark plug as mine doesn’t want to fire up with the original spark plug I brought when it was a 50 there’s spark.
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Post by aeroxbud on Jan 12, 2021 14:46:10 GMT -5
I’ve recently put a 70cc naraku kit in my Yamaha bws ng with original head Doesn’t want to start up when I kick the engine Is there a chance would need to use a different thread spark plug as mine doesn’t want to fire up with the original spark plug I brought when it was a 50 there’s spark. What was the squish when fitted with the 50cc head?
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