HJR 510 motor build issues, please help

[kevshiau]

I had a 10 mil super cub duner built by HJR in January, when I got it back I took it to Glamis to break it in. Initially it felt like the top end never kicks in and the powerband never comes on. I thought maybe because I wasn't giving it full throttle so I finished the break in process as instructed: not going over half throttle for the first 2 tanks. Toward the end of the second tank I took it on a regular ride and tried to open the throttle up, but same results. I rode it around a bit more and the radiator hose popped off the cool head and saw that one of the spark plugs backed out. I took it back down to HJR and he said I was detonating because of the gas I was using (100 pump) it burned off the ground strap on my spark plug. He checked everything and said nothing was damaged or broken and put it back together, and the top end power was there when he tested it. When I got it back it took it back to Glamis this past weekend there was still no top end power, my old 7 mil stock cylinder was definitely faster. Even my friends 421 felt like there was more power. After my second ride I saw that the spark plug backed out again and he said it is because of detonation but don't know what is causing it, it could be the flywheel, stator, coil, CDI, harness, or carbs. I ran VP 100 octane from the can this time, so I am pretty sure it is not the gas. How can I find out what it is causing the detonation and why isn't there any top end power?

I am pretty frustrated because I spent a lot of money building the motor and it has less power and doesn't run right. I don't even know how to find out what is wrong with it. All HJR told me to do was put it back to stock timing and we can go from there, but that means I would have to take my bike back to Glamis and run/test it again just to see if it is still detonating. Is there an easier way?

My mods are: 10 mil, super cub, 32 domes to run 100 octane gas, PWK 38 carbs, aggressive dune/drag port, CPI small bore pipes

[97Screamer]

2 hours ago, kevshiau said:

I had a 10 mil super cub duner built by HJR in January, when I got it back I took it to Glamis to break it in. Initially it felt like the top end never kicks in and the powerband never comes on. I thought maybe because I wasn't giving it full throttle so I finished the break in process as instructed: not going over half throttle for the first 2 tanks. Toward the end of the second tank I took it on a regular ride and tried to open the throttle up, but same results. I rode it around a bit more and the radiator hose popped off the cool head and saw that one of the spark plugs backed out. I took it back down to HJR and he said I was detonating because of the gas I was using (100 pump) it burned off the ground strap on my spark plug. He checked everything and said nothing was damaged or broken and put it back together, and the top end power was there when he tested it. When I got it back it took it back to Glamis this past weekend there was still no top end power, my old 7 mil stock cylinder was definitely faster. Even my friends 421 felt like there was more power. After my second ride I saw that the spark plug backed out again and he said it is because of detonation but don't know what is causing it, it could be the flywheel, stator, coil, CDI, harness, or carbs. I ran VP 100 octane from the can this time, so I am pretty sure it is not the gas. How can I find out what it is causing the detonation and why isn't there any top end power?

I am pretty frustrated because I spent a lot of money building the motor and it has less power and doesn't run right. I don't even know how to find out what is wrong with it. All HJR told me to do was put it back to stock timing and we can go from there, but that means I would have to take my bike back to Glamis and run/test it again just to see if it is still detonating. Is there an easier way?

My mods are: 10 mil, super cub, 32 domes to run 100 octane gas, PWK 38 carbs, aggressive dune/drag port, CPI small bore pipes

Check your timing and your compression. I'm guessing either your compression is too high for 100 octane and/or you have too much timing. If those is inline then your dome design probably sucks. I'm in San Diego if you need help.

[kevshiau]

2 hours ago, 97Screamer said:

Check your timing and your compression. I'm guessing either your compression is too high for 100 octane and/or you have too much timing. If those is inline then your dome design probably sucks. I'm in San Diego if you need help.

Timing is +5 and compression is 150. The domes were cut by HJR. He told me to bring the bike back down to him and he will try to get it fixed. If he still can't get it to run right I may have to take you up on your offer. Thank you!

[registered user]

hey bruh u need plug loks. it loks plugs in so no way they backout at all

[97Screamer]

5 hours ago, kevshiau said:

Timing is +5 and compression is 150. The domes were cut by HJR. He told me to bring the bike back down to him and he will try to get it fixed. If he still can't get it to run right I may have to take you up on your offer. Thank you!

100 octane should be plenty for 150psi. I'd take Kevin's suggestion and put the timing back to stock to see if that fixes it. Kevin does great port work but once upon a time had dome design issues. It its spitting plugs at stock timing and you are sure the compression is 150psi you have a dome design issue. 

[375hp banshees]

^^     U assemble or kevin?

While your in there Make sure you dont have a china timing plate...there #'s are off!

Can Fuel is not oxygenated or anything, is it?

[specialblend07]

Pretty sure RRL had a similar issue with HJR and it was dome design.

I personally would go to a different builder, but that's my opinion.

[375hp banshees]

Speaking of RRL, figured this'd bring him out... hows he doing?

[specialblend07]

Speaking of RRL, figured this'd bring him out... hows he doing?

He’s good. The sex change went well and he’s started using his dilators.


Sent from my iPhone using Tapatalk

[kevshiau]

19 hours ago, 375hp banshees said:

^^     U assemble or kevin?

While your in there Make sure you dont have a china timing plate...there #'s are off!

Can Fuel is not oxygenated or anything, is it?

Kevin assembled it. The fuel I used was VP C10, I bought it off Kevin when I picked my bike up. I will ask him check what timing plate it is when he adjusts it. 

If he can't figure it out this time around I may have to find another builder to get it running properly, another unexpected expense...😩

[SKEETER]

4 hours ago, specialblend07 said:

 

He’s good. The sex change went well and he’s started using his dilators.


Sent from my iPhone using Tapatalk

 

And now hes the face of your favorite beer. 

[375hp banshees]

7 hours ago, specialblend07 said:

 

He’s good. The sex change went well and he’s started using his dilators.


Sent from my iPhone using Tapatalk

 

Good! 

I'm proud of him.

Tell'm it aint boat season gtf back in here

[375hp banshees]

3 hours ago, kevshiau said:

Kevin assembled it. The fuel I used was VP C10, I bought it off Kevin when I picked my bike up. I will ask him check what timing plate it is when he adjusts it. 

If he can't figure it out this time around I may have to find another builder to get it running properly, another unexpected expense...😩

Did he run it too?

Well that eliminates most every issuse ...except tuning.

Like 97 said , he's had issues in the past ( dome/ squish) .

Work with him ; & 97 ; hopefully its something easily fixed.

[registered user]

jfc i machined my own head and it dont rattle plugs out. how long that guy been in business ?

[ClaudeMachining]

My 521 SS is 180psi with 30cc domes and 165psi with 31cc domes. I run 100LL and +5 timing.

So, there is something wrong with your setup, 32cc domes at 150psi should be OK to run on pump gaz....

Do a uccr and squish test and report back.

Envoyé de mon SM-S908W en utilisant Tapatalk