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Author Topic: FCR pumper carb on DR650, installed!  (Read 660 times)

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Offline Hagar

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FCR pumper carb on DR650, installed!
« on: January 02, 2010, 11:07:55 pm »
I had a few days available and fitted the FCR carb that I ordered from e-bay and also fitted the GSXR exhaust.

The carb is from a Yamaha quad, and the canister was bought locally. This mods was discussed in length on the TT website, and is also discussed on Mxrob’s website.  So most of the information is available there.   http://www.thumpertalk.com/forum/showthread.php?t=553922

I started working on the carb. I removed the TPS and turned a plug to fit in the hole left.  This is not really necessary, but it left more room between the IMS tank and the carb.   Because I use the stock petcock I had to make a fitting for the vacuum line.  
This involves drilling a plug out, tapping the hole and screwing it on with loctite to seal it up.

I also turned the swaged in fuel inlet down, to help with the fuel line. I gripped the inlet in a vice and carefully started turning the carb, after deciding that I would make a new one if it brakes.  It turned relatively easy.  (This gave me enough courage to attempt the same thing on my stock BST carb, and it also turned easily.)

The carb also had to be drilled and tapped for the throttle push cable, and a slot cut for the cable to pass through.

While waiting for the 'MX_Rob' FCR39 Complete Jetting Kit’ ordered from Procycle, I started on the adapter.  Mostly a straight adapter is used, but according to Eddie Sisteneros, an expert on these things on TT, this causes too much turbulence in the carb leading to inefficiency.  I did not like Mxrob’s adapter, but really liked the ingenious design of the Noss adapters.


 Unfortunately they are not available for this application.  I spend most of a Saturday to make my own Noss adapter in my garage on the lathe, offsetting the centre with the 4 jaw chuck.  I started of with a solid chunk of aluminum 75mm in diameter and had to bore out most of it from the inside.  It gave me lots of satisfaction to make this part as I am not a machinist by trade and this is a high point in my engineering efforts, but please do not ask me to make you one.  I stuck it on with some silicone.


Meanwhile the jetting arrived and I fitted it as per Mxrob’s recommendation as a starting point.  Also fitted the Merge spring.
I did not want to mess with 2 sets of jetting so had to fit the GSXR pipe before fitting the carb. The jetting information available is mostly for the GSXR/Q2 pipes.   I already had the flanges laser cut, but still needed a mid pipe to be made up.  2 days ago Powerflow in George made me a mid pipe and fitted the GSXR canister.  They did an excellent job for a modest amount, and also had to contend with the irritating owner looking over the shoulder.


With this obstacle finally out of the way, I cut open the top of the airbox and fitted the carb.  I decided not to fit the stock bar mounted choke for now, will decide later  if i will connect it or stick with the hand pulled one under the tank.

What is it like? A lot more fun.  Power noticeably more, most likely because of opened airbox, lifts front wheel without clutch, engine feels opened up.  A lot easier to initiate power slides immediatly when wanted.  At the same time more relaxed.  I went on a 100km cruise to Jonkersberg this afternoon, I needed to shift less than normally, as i can drop down lower in 5th than before and accelerate without stumbling.  Engine feels happier.  Does not feel over geared any more, able to crawl slower.  This was particularly what I was after.  It is not night and day and I guess it depends on kind of riding you do.  For me this changed the bike in the one I wanted.  The GSXR pipe has a low throb when idling, almost like a Harley, for me too much so.  I like it on the road and the bike sounds less like a sowing machine but for me it is a bit too loud in built up areas. (don't want to irritate other people)  It does not really make a lot of noise when cruising though.  The carb makes a twirping sound almost like a turbodiesel when accelerating.  I am still playing with the fuel screw, and i am getting some decel popping, not too loud though.  I really enjoyed my ride this afternoon, back tire is not going to last.  Filled up precisely before and after the trip, got slightly more than 20km/liter. i was worried about fuel consumption.  while i definitely had more fun than normally, I actually used less fuel than I normally would have used.  I will see what it does on more open road cruising at higher speeds. My craving for a wide band O2 sensor lessened slightly, after the good consumption i got this afternoon, but I would still like to play with the jetting.

I know it is not needed, but it is a toy after all

« Last Edit: January 02, 2010, 11:16:36 pm by Hagar »

Offline sidetrack

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Re: FCR pumper carb on DR650, installed!
« Reply #1 on: January 02, 2010, 11:21:34 pm »
Good job that carb is worth every cent  :thumleft:
Little by little, one travels far
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Re: FCR pumper carb on DR650, installed!
« Reply #2 on: January 03, 2010, 08:22:47 pm »
Nice post :thumleft:

Offline jenks

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Re: FCR pumper carb on DR650, installed!
« Reply #3 on: January 13, 2010, 06:42:14 pm »
Very nice report, Hagar. Well done! So you think it was worth the graft?? Do you think the engine is taking more strain now because of the increased responsiveness??

Cheers boet!
dr650se "Honest Joe"