R1200GS Forum banner
1 - 7 of 7 Posts

Airheadguy

· Registered
Joined
·
2 Posts
Discussion starter · #1 ·
Im at a loss here can anyone help.
2018 BMW R- Nine T - bored out to a 1300- Akropovic Ti exhaust into a single carbon can. High compression motor

Here are the symptoms with no regular frequency or ability to recreate . But this happens at least once a ride.
Symptoms:
#1 Engine temp on the digital read out starts to climb rapidly
#2 while temp is climbing the bike has noticable engine braking and a it is struggling to accelerate
#3 Will not rev out quickly with clutch pulled in or hit max RPM with clutch pulled in.
#4 this continues for a while- temp goes to 289F on digital read out.
#5 pulling in the clutch and revving the engine feel like its no fully disengaged . But it is.

So lots of symptoms and things going on there. And as oddly as it starts it stops and the engine temp starts to slowly fall and then the bike operats as normal.

Feel like it’s only firing on one cylinder or miss firing to me.
Im thinking Coils? Spark plugs? Need higher octane fuel?

Any thoughts.
 
Welcome to the forum.

Stock ecu/fueling? If you bored it out and added free flowing exhaust it could be running extremely lean. What fuel are you running that you ask about higher octane?
 
Wildly over advanced ignition timing will cause very high temperatures as will excessively lean / rich mixtures. Such drastic engine changes require remapping of the fueling and ignition curves. In closed loop the engine will run OK, but under open loop your fueling / spark could be way off in certain load / RPM ranges.

If the bike runs OK when at full temperature except for short episodes of this, I would start with a check of the function/mounting of the cam/crank angle sensors and put a fuel pressure gauge on it while riding to see if the pump is intermittently failing.

How do the plugs look?
 
Discussion starter · #5 ·
Welcome to the forum.

Stock ecu/fueling? If you bored it out and added free flowing exhaust it could be running extremely lean. What fuel are you running that you ask about higher octane?
Seems fine on Cam 2- Im currently travelling in Canada and can only buy 91 Octane. No 93 at the pumps where I am visiting. All this summer I’ve been running VP Cam2. And it didn’t do this. Now on lousy pump gas its acting up. Could be fuel related.
 
Cam-2 is 110 octane. If you motor requires that hig of octane no doubt its not going to be happy on an octane 20+ points lower. Wait until you get to a gas bar that only has 87 octane. The pistons will probably eat themselves.

IMO, silly to build a high compression engine for a daily driver that requires fuel that is not readily available.
 
2018 BMW R- Nine T - bored out to a 1300- Akropovic Ti exhaust into a single carbon can. High compression motor
Seems fine on Cam 2- Im currently travelling in Canada and can only buy 91 Octane. No 93 at the pumps where I am visiting. All this summer I’ve been running VP Cam2. And it didn’t do this. Now on lousy pump gas its acting up. Could be fuel related.
You found your problem and solution.
🙂

I can’t say whether a bottle of octane booster will help the 91 enough to eliminate the problem but worth a try. I used to keep a bottle on my GSA for trips in case I could only get 87…never needed it and later learned here the standard oil cooled engine can take a tank or two of 87 without problem.
 
1 - 7 of 7 Posts