daveopam

My Feedback: (9)

Be sure and post how it went. I would like to know, plus you never know who else is reading.


David

Navy_Flyer

I don't get anywhere near this RPM. With a Saito 125 and APC 16-6 running YS 20/20 fuel I get a max of approx 8450 rpm. Don't know how other folks reporting higher RPM are getting those revs.

the Wasp

My Feedback: (1)

I don't know what type of engine mechanic you are, so I have to ask the questions that I know that others have found wrong with their 4sts.

are you sure both your Tapet Lashes are adjusted correctly? they each should be .0015"
also check to see if your Carb's Cat's Eye is pointing straight into the Intake Manifold.
make sure your upper Pushrod Tips are inserted/seated correctly.
are you sure that both upper and lower O-rings that seal the Intake Manifold are not leaking.
are you using a quality Glow plug. I don't know why, but I have seen people run cheap, junk Glow Plugs in their $500 4st.

Jim

Navy_Flyer

Hi Jim,
Everything is correct. Engine was returned last year for servicing and received new bearings, and test run. I bought it used and after one tank of fuel it seized. Horizon said bearings were rusted. Connecting rod was worn. All replaced. The glow plug is factory Saito plug.

the Wasp

My Feedback: (1)

so you have checked the Tappet lash ?

Jim

1200SportsterRider

Saito 1.25 MA Classic 16x6 10% Wildcat/18% full synthetic, max 9,025, idle 1,650
Saito 1.25 Graupner Grey 15x8 10% Wildcat/18% full synthetic, max 8,785, idle 1,700

These are my numbers with 10% Wildcat 2/4, 18% full synthetic, stock exhaust and Glo-Devil 4c special. And this velocity stack, the extra one went to Captain Crunch

Navy_Flyer

Yes. I just took off the valve covers, and with both valves closed, the Intake valve lash was too loose. Didn't measure it but I'd guess it was about double from factory new - probably around .008. I reset it using the factory feeler to a tight .004. Exhaust was perfect. I'll test run now to see if it made a difference/

Navy_Flyer

Just test ran the 125 after the valve adjustment. I saw a little improvement. With Byron YS 20/20 fuel and APC 16-6 prop, got 8620 peak, idle at 2100 smooth transition. With PowerMaster 10% nitro/18% lube, did only 8450 peak, but idle was a bit better at 1950. Bad news is that after the run I noticed that the valve cover gasket on the exhaust side was torn. So I need to replace them. The feeler gauge that came with the engine measures .004, and instructions say .002-.004 is correct. Don't think I'll get much better than this until I get more fuel burned.

the Wasp

My Feedback: (1)

OK the RPM came up some, setting at .002 should get it up a bit more. but how much fuel has been run threw it since the rebuild, maybe it needs to Run-In more.

Jim

Navy_Flyer

Im estimating 1/2-3/4 gal of fuel max.

1200SportsterRider

NF, if it has been run for 50 minutes or so, it won't improve much from there. The 125 is a 9,000 rpm engine and should be propped for that. If you have an extra Saito choke clip I'd gladly make you a more suitable velocity stack. The stock one is smaller than the 125's venturi.

Navy_Flyer

There is no velocity stack on my engine. This is their 'newer' engine, no choke or stack. Are you saying a 16-6 is not correct? I don't get much better with a 15-8 either. Both props are recommended range by Saito. Maybe I should run a 16-5 or 15-6/7?

1200SportsterRider

It depends on the plane style, high wing, flat bottom wing, the 16 x 6, low or mid wing, symetric airfoil 15 x 8 would be better. I know that's kind of general but ball park. 15 x 7 three blade is a good choice also.

Navy_Flyer

Flying a Seagull Bucker Jungmeister biplane, weighs 13 lbs.