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DR440 jetting start point for safe run in

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Hey guys im looking for some help please, I have just over hauled my motor and made many many changes along the way now what i need to know is a safe start point for startup/run-in .

I have a 1991 Dr350 mods and specs as follows.

- 440 cc pro cycle big bore kit JE 89 mm 10.5:1 piston.

- New valves,guides,cnc ground seats.

- Improved porting intake and exhaust.

- High flow alloy air box,Uni filter dual layer foam filter.

- complete bottom end over haul crank rod bearings ect.

- larger header and muffler 1 1/2 " 38 mm I/D.

- carb that i am fitting is a FCR 37 mm off a 04/05 CRF 250.

http://global.ebay.c...0753490759/item

- Kick start manual de-comp.

Riding conditions.

- I live at Sea level and do most riding around the low lands

- temp ranges from -7 dec c in winter to 30 deg c in summer

- I ride mostly single trails and enduro style riding

- Zero road riding

I think i have got it all in there Sorry if I have forgotten anything. Once i have a base line i am capable to refine my own jetting. As it is a new carb to me I would just like a base Line for startup

pilot,needle pos,main any setup for acl pump setting would be great.

Any feed back would be very helpfull

Thanks

Edited by bad-mod

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Ok carb arrived today and the jetting that is in the carb is

- Needle NCYR middle clip

- Pilot 42 aj 100

- Main 160

the parts fiche lists two diaphragm's #15 and #20 how do i know which is which for replacement and what diff will they make ??

Edited by bad-mod

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Ensure the carb is in good condition. Install it. Ride the bike, break in the engine. Then with a hot engine, you can do the pilot/fuel screw stuff, do a under load 4th gear

WOT ride to check/select the main the do the needle. Then you can worry about the AP and the diaphragm. Chances are, you are going to want the shortest rivet and no leak jet.

I think you may find a 37mm carb is a little small for a 440.

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Ensure the carb is in good condition. Install it. Ride the bike, break in the engine. Then with a hot engine, you can do the pilot/fuel screw stuff, do a under load 4th gear

WOT ride to check/select the main the do the needle. Then you can worry about the AP and the diaphragm. Chances are, you are going to want the shortest rivet and no leak jet.

I think you may find a 37mm carb is a little small for a 440.

thanks william do you think that jetting combo will be close enough to get it running ? with a new engine should i also be worried about leaning out ?

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It should be fine.

With a 4S, you cannot damage it by being too lean. That said, I would not do any long (over 1 minute) WOT runs until you are positive the main is right. Google 'Moto Tune.

FYI-Do not try and do plug chops, unless youm are a pro and use race (not pump) fuel, it is a waste of time.

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It should be fine.

With a 4S, you cannot damage it by being too lean. That said, I would not do any long (over 1 minute) WOT runs until you are positive the main is right. Google 'Moto Tune.

FYI-Do not try and do plug chops, unless youm are a pro and use race (not pump) fuel, it is a waste of time.

i normaly use av gas, 120 octane

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Way too much octane. You should run 89 with your engine. Anything higher and you are giving away power.

AV fuel is for slower turning, high altitude, high compression engines. It is also formulated tot deal with moisture issues and long periods of time of inactivity.

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Way too much octane. You should run 89 with your engine. Anything higher and you are giving away power.

AV fuel is for slower turning, high altitude, high compression engines. It is also formulated tot deal with moisture issues and long periods of time of inactivity.

sweet good advise thank you very much

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