DS650 compression

[H0nDo]

Im about to purchase a 04 DS that seems too good to be true...it is clean, i rode it today, it ran good....but I want to check the compression before i fork over my money. I cant seem to find any specs on the compression of these motors...can anyone help me out?

Thanks
Seth

[Caseys 300ex]

how much is it?

[DieselBoy]

Sorry, don't know how much compression their supposed to have. Search for a DS650 forum, you can ask them.

Bombardier DS 650 Technical Specifications

ENGINE - SPECIFICATIONS

Type 4 stroke, 1 cylinder, 4 valve, double over-head cam
Displacement 653 cc
Cooling Liquid cooled
Maximum RPM 7700 rpm
Starter Electric start; start in any gear
Lubrication Dry sump
Decompressor Automatic
Carburetor Mikuni BSR42 / Manual choke
ACG 290 W range - DENSO
Maximum dry weight 470 pounds
Clutch 1 multi-disc

COOLING / DRIVE TRAIN

Radiator Front mounted
Coolant Glycol / water 60/40
Transmission 5 speed, manual clutch
Rear Chain drive / Solid axle

SUSPENSION

Front type Independent suspension / double A-arm
Front travel 12.0 inches travel
Rear type Rigid swing-arm
Rear travel 11.5 inches travel

BRAKES

Handle bar control R.H. front wheel brake
Foot control R.H. side RR wheels
Front 2 drilled hydraulic discs
Rear 1 drilled hydraulic disc
Parking R.H. brake lever includes a lock on front wheels

DIMENSIONS

Overall
Maximum height 47.5 inches
Maximum length 77 inches
Maximum width 48.5 inches
Wheel base 49 inches
Turning radius 124 inches
Fuel tank capacity 3.5 US gallons
Tires front 21 X 7 X 10
Tires rear 20 X 10 X 9

LOADING CAPACITY

Total 275 pounds
GVWR 750 pounds

GROUND CLEARANCE

Front & under engine 11.7 inches
Rear Axle 4.75 inches

INSTRUMENTATION

Pilot lamps Neutral indicator
Oil pressure / coolant temperature

EQUIPMENT / ELECTRICAL / OTHERS

Battery 12 V, 13 A dry type battery
Headlight 60/55 W
Taillight & Brake light 8/27 W

[GPracer2500]

That engine has an auto decompress you should know about if your going to check the compression.

I *think* you should be near 120psi just spinning the motor with a tester connected. With the auto decompress disabled it will be higher at something around 200psi.

I believe those engines are pretty stout (durable). But if you have reason to believe there is something off with the engine it might be worth talking to a Rotax mechanic about how to check compression. Or (second choice), find a service manual to look at.

The Rotax in the DS has 9.6:1 compression. The same Rotax except with EFI and a different tune has 11.5:1 in the BMW F650.

[H0nDo]

Thank you GPracer, that helps me out a lot...ill post and let ya know what happens later tonight...

Seth