Triumph Unit 750 Big Bore Kit

[Torch]

one more question, what ballance factor did you set it at?

[Guest]

78%

[Guest]

< oil getting thinner when it's hot.>...the advantage to using a multi weight 20/50 oil is it is supposed to be ...20 weight when it is cold and 50 weight when it's hot.

TRue to a point , as viscopsity additives break down due to use., as oil heats up it doesnt thicken like it did thereby viscosity rateing lowers under presure so pumping more oil to crank can only be a good thing , road bikes dont change oil every 800 miles or so where the additives work correctly

[Torch]

78%

later model Triumphs were balanced at 85% , what was the reason you went with a less balanced set up?

[Guest]

later model Triumphs were balanced at 85% , what was the reason you went with a less balanced set up?
and on the PWK carbs are they the 28 M/M ones?

I talked with a few engine builders (machinist forums) and asked what they were using on there motors. It seems that if the crank is dynamic balanced, and the pistons/pins/rods are weight/height matched you can push the useable (relatively) vibration free R.P.M's up toward 8000 by using a lower factor. I've had my motor to 7800 so far, It's shaky, It will rattle your fillings out. with the factory balance my motor was happy at 4k, but would kill you at 6k. Now it seems happy at 5-6k.

Yeah, 28mm #138 mains.

[Torch]

I am always interested in learning new ways of engine building , would you care to share some build info? like ....
valve size, cam timing, porting photos, are you running stock rods at 7800 rpm?, is that rpm where your power curve is at? have you done any dyno runs on it? , if so what are the readings?

[Guest]

I am always interested in learning new ways of engine building , would you care to share some build info? like ....
valve size, cam timing, porting photos, are you running stock rods at 7800 rpm?, is that rpm where your power curve is at? have you done any dyno runs on it? , if so what are the readings?

Stock valves?, (stainless exhaust, steel intake) LOTS of porting, (rocker box bolt holes opened up then sleeved) fresh 3 angle cut, Stock 750 rods with 650 rod bushings pressed in, Power comes on at 5000 rpm, keeps pulling till I get scared and shift. JOMO 15 cams, 35* BTC intake, 66* BBC Exhaust. Nope never did any dyno runs.

[sleethmitchel]

i had a 'drop in' 800 cc MAP kit installed on my t140. the instructions that MAP provide tell you to re-torque the heads 'EVERY 500 MILES'!!!! i have never got even 100 miles before the headbolts vibrate loose with loss of compression and power. the mechanics pushed my bike home after 2 miles of a test ride. they have assembled
and re-assembled this piece of crap three times now. and if you wanted to putt down to florida from st. louis, you
had better take a cubic buttload of extra rockerbox gaskets and a torque wrench in your back pocket. i'm putting the stock cylinders and pistons back on. what's 50cc's anyway?

[Guest]

so youd say keep away from the 800 map kit , how was the motor when it was 750

[Torch]

we have used the 750 billet alluminum kits from Map and didn't have any problems, we heat cycle the engine and re-torq it 3 times before we take it for a ride.

[osidebarrel]

Torch & TigerChris great rebild info. Just tore down my 650 and been wondering what direction to head, this helps tons

[Hepcat13]

Yeah for real. I got a good deal on a Morgo kit and I thought it was a bolt on kit. Now I'm definitely going to have to measure it. I don't have the coin to balance the crank though.

[Torch]

Yeah for real. I got a good deal on a Morgo kit and I thought it was a bolt on kit. Now I'm definitely going to have to measure it. I don't have the coin to balance the crank though.

most of those "drop on" kits are not really a plug and play deal, almost all of them are set up at about .002 and need to be honed to the correct piston clearance of .0045, we see a lot of them that will stick the pistons after about 15 minutes of running,

[Hepcat13]

Thanx, for the info. I'll be pricing out machine shops on Monday.

[Guest]

if its a morgo it should be ok outa the box