Engine Woes maybe?

[jwebfournow]

Hello all!

I've been lurking for awhile, since last working on the GS1100G, I have to tell you that I ended letting the previous owner have his bike back. After all the work I had done to it, paint and carbs,tuning it was back to it's former glory and it was a monster, the PO had to have it back and made me an offer that I couldn't refuse. In the meantime I'm looking for another GS, so while I wait I have picked up another bike for the winter. Don't shoot me just yet! It's not a GS. I am having an issue with it not quite sure what direction to go. Low mileage Honda Magna with 3k Been sitting since 92, compression across all 4 cyl. is 140psi book calls for 180 +/- 28. pulled carbs and cleaned, starts up, hookup Carbtune to sync no readings straight across until I reach about 3k rpm, does not smoke,bad rings? I could understand one cyl but all 4. any ideas? i know this is not a Honda board but the knowledge base here is phenomanal. So as to not tie up the board if anyone can email me privatley I would appreciate it. Thanks

[chef1366]

I'd ride the bike awhile to reseat the rings since it's been sitting so long.

[SqDancerLynn1]

Where are you hooking up the carb tune ? Could it be ported vacuum ???
Yea I would go ride the shet out of it for an hour or two and recheck it

[jwebfournow]

The hookup is the same as the GS. right at the intake manifold. I'll have to get some hours on it. I was thinking of shooting some Marvel mystery down the cyls and letting them set for a few days also. Have to put a tire on front before its roadworthy. Maybe stuck compression rings? but all 4 cyl, bike has only 3k on it, would be a shame if compression won't come up.

[rustybronco]

compression across all 4 cyl. is 140psi book calls for 180 +/- 28. pulled carbs and cleaned, starts up, hookup Carbtune to sync no readings straight across until I reach about 3k rpm, does not smoke,bad rings?

The hookup is the same as the GS. right at the intake manifold.

Maybe stuck compression rings? but all 4 cyl, bike has only 3k on it, would be a shame if compression won't come up.

That bike should run just fine with 140 Psi compression readings. the reason for not showing any vacuum readings isn't because of the rings.

can you find or borrow a Vacuum gauge and hook it up to each of the intake ports one at a time, then record the readings for each cylinder? did you bench sync the carbs before putting them back on?

are you sure the problem's not in the way the carbtune is hooked up?

http://www.carbtune.co.uk/inst.html

Most bikes have readings higher than 8cmHg, but some bikes such as R-series BMWs and two strokes can have readings lower than this.

if the throttle plate opening is too great at idle the vacuum readings will be lower.

[jwebfournow]

On these carbs I never broke them apart from the plenum,so the nothing was really disturbed in that regards. I pulled all the jets and cleaned, then went over the rest with berrymans spray and hit all the orifices I could get too. I did not soak them. Probably should have. It starts fine. I was concerned when I went to check sync and they did not even register. I'll flip the cartune as per intructions and see what happens. Thanks for that info.

[Nessism]

My guess is the bikes fine but there is some quirk in your gauge set or the way you hooked it up.

If that model bike uses a vacuum petcock, make sure the line is plugged when performing the sync.