GPR Camp: Replica Racers

Was up early this morning for the installation. It went well and I even made it to the meet up mostly on time.




Mostly I took photos of the parts coming off the bike, and a few of them on the bike. Started running out of time, and the photos suffered. The fluid in the reservoir was a decent color, but it was contaminated so I removed it all. With minimal bleeding the system was up and running. It worked great all day. This master is a little bit too much for the caliper though. Feels a little bit much like a rock. But it should be a good match to the Brembo caliper then than eventually gets installed.

Looks like it spent Derbi de Mayo hanging out in Memphis. Might even show up today considering that it has already made it to South San Francisco. I do wonder about the time stamps though as those do not appear to be the local zone.

The NG Freno disc showed up yesterday. I didn’t hear the Fedex Cat so I had to go to the Local Drop-off Point.


It was packaged very nicely.


And of course some pr0n images.

Right at the end of the ride the bike was having a lot of trouble revving. We tried a bunch of things. Even thought it was a fouled plug, and replaced it to no avail. Still have no idea what’s up. It was running strong all day. It idled nicely. Seems to be super happy, until it wasn’t.


The plug is a bit black, but as I was trying to get the bike to rev lots of black smoke came out the pipe. This didn't change at all with a brand new plug. With the compression gauge I could only get a little bit over 100 psi. Not too different from what I saw previously. The max I’ve seen with these Stage6 Big Racing kits has been around 120 psi.







There is some scoring on the cylinder walls, but nothing that should be causing this issue.

Anything unusual with the airbox, intake snorkel, or carb in general? Any way something could have blocked the intake?

Seems like a air or fueling (carb) issue to me.

When the cylinder failed Greg came out to rescue me.


Last night I did some reading on checking the compression so I went out to check it again today. Now it will only go a bit over 75psi—very much like what happened with the Silver bike. I really becoming convinced these cylinders fail very quickly.

To answer to J’s question. When this first happened I disconnected the air box to ensure it wasn’t the issue.

Maybe a broken ring could cause this. Will you pull down the cylinder? Its just a 5min job

toratora wrote: ↑

Thu May 09, 2019 12:39 am

Last night I did some reading on checking the compression so I went out to check it again today. Now it will only go a bit over 75psi—very much like what happened with the Silver bike. I really becoming convinced these cylinders fail very quickly.

To answer to J’s question. When this first happened I disconnected the air box to ensure it wasn’t the issue.

Bummer.

What cylinders are those again?

kaldis12 wrote: ↑

Thu May 09, 2019 4:14 am

Maybe a broken ring could cause this. Will you pull down the cylinder? Its just a 5min job

It would be way more than five minutes—it takes longer than that just to remove the plastics. Both engines are going to be opened up eventually. I’ll probably pull the engine out of the Silver bike, and put a stock engine in it for now.

jkv357 wrote: ↑

Thu May 09, 2019 6:27 am

Bummer.

What cylinders are those again?

Yeah it sucks. Especially since both kits are suffering the same symptoms. I checked in with some folks that have these kits, and they stated that the most they get before needing to do the rings is 1000km, which is about 600 miles. That’s racing engine level servicing, but even then they would still run. These kits wont even run. It could be possible that the just came with bad rings

These are the Stage6 Big Racing 77cc kits with the new style heads. I’ve ordered a Metrakit ProRace 3 70cc kit to install on this bike—it was the only decent kit I could get in time for the 19/19 ride. It wont have as much power, but it will be way more reliable than the Stage6 kits have proven to be with my bikes. I am really surprised that these kits would wear out so quickly.

Oh yeah sorry. I forgot that you have to remove the plastics and remove the engine. I can just remove the cylinder in 5mins, with almost no fairings

It sound me a ring issue, my buddies had about the same simptoms as your bike. Never give up, I would be really interested in how does the 77 and 88 compare to each other on a video. You will have to do one decent video for us keep it up