I need exhaust info / photo

[PGlaves]

I have a 2001 F650 Dakar. A previous owner removed something to open up the rear of the left side exhaust can (catalytic converter). The bike now barks more than I like but I could live with that. The bike also has a horrible "dead spot" in power delivery right at about 4,000 rpm. I am fairly certain that the change in exhaust flow is causing the performance problem. Before I go further I intend to plug that opened up exhaust.

I understand that in OEM trim the rear of the left side can was mostly closed but there was a small hole or stub which allowed a little flow. I'm not sure of this though.

I would like a decent picture of the rear of an OEM left side can (catalytic converter side) of a single spark F650GS or Dakar. And if there is a little opening back there, I need to know how big that opening is.

Can anybody help?

Thanks

 

[f650624]

Cat

I don't have a caliper, but 5/16" is close. There were instructions some years ago at The Chain Gang (www.f650.com) on how to pull the "plug" out of the cat for more noise. I never did get in to the more noise thing.

 

[sgborgstrom]

Interesting, I've been riding my R100GSPD for the past month or so but IIRC my 2001 Dakar is just starting to sing at 4000rpm.

As far as I can tell my exhaust hasn't been tampered with, very little flow actually comes out of the pea-shooter on the left side. You might also take a look at the air intake snorkel, a lot of them were trimmed in an effort to solve the surging/stalling problem some of the 2001 models were plagued with.

 

[PGlaves]

Thanks. That will get me started restoring the exhaust anyway. Then I'll see what I have. Something is amiss because it just loses power at 4K, but if coaxed above that rpm or if I take it up in a lower gear then it starts to pull OK again.

 

[sgborgstrom]

Updates?

 

[PGlaves]

I found several "things" that I have dealt with. A beer bottle cap is a perfect press fit into that pipe. I have experimented a bit with the size of the hole I want in its center.

I found a dozen or more holes drilled into the intake snorkel. Taping over them didn't make much difference one way or another.

The previous owner apparently had a Techlusion attached - the Scotchlocks for spade connectors were still on the two wires to the injectors but no device was connected.

Messing with this stuff made no difference. So, since the service records indicated it had a valve adjustment just before I bought it I went digging to see what I could find there. Well, the valve adjustment was spot on. But the cams were not in the correct position. I found the exhaust cam one chain tooth advanced and the intake cam one chain tooth retarded. I corrected that and the performance problem went away. It pulls well and is now capable of felony speeding.

So two days later the battery shot craps, but the new one should be here in a day or two.

I will do a little more experimenting but it seems to run fine in stock configuration and the fuel mileage jumped from right at 40 to 56 mpg the first tank after I reset the cams.

 

[sgborgstrom]

At least the cams weren't so far off as to cause any damage! Managing the timing chain is a fun bit of work when you have to replace those shims but the sprockets are pretty well marked, somebody had an off day in the shop.

While you are messing around with this bike, I've been running a 16/49 tooth sprocket combination (stock is 16/47) for quite a while now. Most of my F650 time is non-highway commuting and fire roads, the 49 tooth rear gives you a little bit more zip around town without getting too buzzy on the highway. IMO the 15 tooth front is a bit to low on the road.

 

[PGlaves]

At least the cams weren't so far off as to cause any damage! Managing the timing chain is a fun bit of work when you have to replace those shims but the sprockets are pretty well marked, somebody had an off day in the shop.

While you are messing around with this bike, I've been running a 16/49 tooth sprocket combination (stock is 16/47) for quite a while now. Most of my F650 time is non-highway commuting and fire roads, the 49 tooth rear gives you a little bit more zip around town without getting too buzzy on the highway. IMO the 15 tooth front is a bit to low on the road.

I may play with the chain/sprocket gearing next time it needs a chain and sprockets. What is on it are new. The bike loves any speed up to and a bit over 80, and is capable of triple digits. I don't find any of the cruising rpms to be objectionable. This bike will be my summer traveling bike this year (assuming I trust it by next month). I expect to put 25 to 30,000 miles on it between May and September. We'll see how that all works out. I do have my K75 and my R1150 ready to go too, so might switch bikes a time or two as opportunity or necessity dictates. But I reallu intend for this bike to see Alaska and Pennsylvania, and most spots in between this year.

 

[sgborgstrom]

Sounds like and excellent plan. We will be expecting pictures!