well Im having a bogging issue with my Honda CR125 elsinore. Its a 75 model and since you guys are better on this site at suggestions than the Honda forums, I thought id ask on here again. (the MR175 runs fine thanks to all that helped me find a Yamaha piston swap.) following the manual I blocked off the intake and exhaust ports and pumped it up to abut 10 psi. manual says a pound or two a minute and its bad. It was on the border line of losing the pressure per manual. I attached pics of the oil dipstick hole with soap bubbles coming out. that was the only leak i could find. no leak on magneto side. Is that enough to cause my severe bog from idle all the way up the powerband? It loads up so badly it can pull itself. Compression is 120 psi it starts easy and idles well. Carb swap and timing changes did not change anything. idea?? thanks

Different train of thought, but if the previous owner idled the bike and didn't ride it hard, exhaust could be plugged up and needs to be burned out.

I checked that. clean pipe. even removed it and air filter made no difference.

If you have air bubbles around your oil filler cap you've got pressurized air getting into the clutch side. Bad crank seal on that side would allow engine oil getting sucked into combustion chamber, I.e. loading up.

To confirm, pop the clutch cover off and do the soapy water test around the clutch side crank seal.

As you've stated your leakdown rate is close to the spec you have found. I'm certainly not an expert on leakdown rates but I can share some knowledge.

When checking, I find that rocking the fylwheel to and fro helps highlight a worn out crank seal. The leak rate will increase noticeably over the crank setting stationary.

After sniffing out and correcting leaks on 360 cc engines I've seen rates where 7 psi would drop to 2 psi over a 24 hour period. A very slow rate. I say this because it seems the rate you are observing could be improved upon.

Others have mentioned that leak rate testing by pulling a vacuum is a valuable test because some seals will leak under a vacuum at a greater rate than under pressure. Of course, the seals need to be effective at both positive and negative pressures.

Would like to hear a video of what its doing. My first thought was something blocking exhaust & still wonder if that's the case. If you live miles out in the country you could try it briefly minus the exhaust to prove or disprove a point. I'm thinking by 'bogging' you mean super rich which can be things like something blocking the air filter. I've seen rags left in places causing that sort of thing. Main jet left out of the carb etc. They were piston port motor so can't pick on faulty reed valves. On the other hand if you mean it 'gasps' on opening throttle then it sounds lean--so the ideas for things to look at start on a different road. Will it not rev up at all?. Or are we talking ignition where it'll start & run slowly but the stator coil that runs the higher revs is faulty. Sorry no help am i--well not yet. I raced one of those new out of the box & were a great little bike, had a 250 too but preferred the 125 on a rough track.

Here's my blocked exhaust, plus showing a seal that's blown out of the case behind the magneto. Not CR125 Elsinore but same principle for bogging 'big time'--then gasping due to being lean in other pic. Well it was 'that lean' it wouldn't run lol.

thanks ordered seals and gaskets.

yeah, been easier if it leaked down right away, always get marginal results. be tearing it down. thanks

i check the carb, ignition, ect. be tearing it down. thanks