Jonathan.Lam

hi
i've got the saito 125 can i just ask wat is the difference between a big and small gap in the valves

thanks

NM2K

My Feedback: (14)

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My first G2300 Tigre would have tipped my sawhorse over had I not been there to catch it!

I ended up putting an I-bolt in the tail end of the sawhorse and fastening it to the chain link fence. End of problem. Even the G62 can't make a dent in the chain link fence.

I love the powerful thumping sound of the large Saito four-strokes. Especially when they are consuming relatively high nitro. Then again, I'm an ex bassist, so I guess that explains that.

w8ye

My Feedback: (16)

A small gap would be like .002" or less. A Big gap would be .004" or greater

Jonathan.Lam

wats the difference - does it make the engine go faster wen it is smaller


???

kochj

I thought this would be the place to ask this question\!!
I have a saito engine that as it is right now seems worn. It has diminished amount of power, not flipstart and idle reliably when warm. all signs of being worn out.... I didn't run more that 3-4 gallons of specified 30% coolpower fuel through it, but maybe ,because it was when I started to get into nitro engines that I ran it lean. It never idled well for me even when new.. I replaced it with a updated fuel needle kit with no change, even when I leaned the heak out of the idle needle.... The question is, If I replace just the piston ring, am I wasting my time...\???????? OR DO YOU have too replace the cylinder and ring in order for it to give me know power\>>????

Thanks
Justin

N1EDM

My Feedback: (2)

I don't think that you did the engine any favors running it like that, but you might first try re-setting the valves.

Other questions to ask - has the plane been in a crash lately? Had you changed the HS or LS needles before you began having these problems?

Just some thoughts.... Anyone else?

Bob

Thunderchild

Hello again Hobbsy,

Did you manage to get an answer from the shop on this?

TC

skiman762

Not sure if glow 4 stroke are the same as gas engines but when the valve gap is on the wide side it causes the timing to be late the engine will have a loss of power
If I can remember from my hotrod days if the valve lash is increased .004 inch the cam duration is changed buy about 10 degrees enough to notice a difference
too tight can cause idle problems

this is from comp cams I knows it car stuff but it applies

If the intake valve opens too early, it will push the new charge into the intake manifold. If it occurs too late, it will lean out the cylinder and greatly hinder the performance of the engine. If the exhaust valve closes too early it will trap some of the spent gases in the combustion chamber, and if it closes too late it will over-scavenge the chamber; taking out too much of the charge, again creating an artificially lean condition.

Hobbsy

My Feedback: (102)

I found out on my 1.25 that setting the valve lash at .002 instead of .004 costs about 120 rpm and causes full throttle hunting.

Sorry TC, they are sold separately.

rajul

My Feedback: (58)

Hobbsy, what are you referring to by "full throttle hunting"? My valve lash is set to 0.002" but I don't see any issues, though it's on a Cline reg.

NM2K

My Feedback: (14)

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I'm with Bob on this one. Reset the valves first and change out the glow plug. Then if it needs a piston ring...

Is the compression down a noticable amount? If not, the new ring will not be of much benefit.

Thunderchild

No problem. Thanks for chasing it up Hobbsy. Sorry to be a pain but:

So the part number in the corner is for a spinner? Do they have part numbers for different diameter spinners? I don't seem to be able to make sense of their listing.

If you could help out a slow old fella, I'd appreciate it.

Thanks

TC

RCSPORT FLYER

My Feedback: (11)

I have 2-30's
1-45
1-50
1-56
1-65
2-80's
1-91
1-120
2-150's
1-220 Can I get a number please? Thanks

kochj

ASSuming you have done all of the right mainatence with a saito engine and it is worn out from use\:
can you replace just the ring, or do you have to replace both the ring and piston and cylynder to get back the compression\???

anyone \????

w8ye

My Feedback: (16)

The Saito cylinders normally don't show much wear unless metal filings go up in the cylinder.

I've repaired two old 91's in the last year and I put a ring in one. The other, I put a piston in also because the piston had little pieces of steel embedded in it. Both engines run like a top.

Normally replacing the ring will be good enough.

There's another thing on the Saito are the cam and lifters. You look for wear on them when you have it apart.

All of the long use high time Saitos I've taken apart had a least one bad lifter.

RVM

Anyone have any information on the "hot" cam/crankshaft replacement for the mid-block Saitos?

w8ye

My Feedback: (16)

The hot cam is the one and only available SAI6535A that came out in the mid nineties. The original cam was the SAI6535 which is no longer available.

The -A- cam is the one referred to as the "High Cam"

It is used in the 65,72,80,82,91,100,&125

RVM

Ah ok so nothing that would change performance in any way then... thanks!

Zombie

Dimple towards the rear.

Bob93447

JettPilot,

You made the suggestion that I check out the backplate of my Saito .72 as a possible cause of the missing RPM. Since I don't know the difference between the old and new backplates, I have attached a picture of the one that I have. Can anyone tell me which one that I have from this picture. I purchased the engine from Chief in July of 2003.

Thanks,

Bob

rajul

My Feedback: (58)

That's the new backplate with webbing reinforcement for the carb lug.

rajul

My Feedback: (58)

Did see any freeplay between the intake manifold and cylinder? Also, did you try changing your plug and using fresh fuel? What's you valve gap set at presently?

Bob93447

Mike,

No, I did not see any freeplay between the intake manifold and cylinder. It has never been taken apart until now -- but there is no o-ring in the manifold to cylinder seal, just a tight sliding fit with a metal washer on the outside. I last set the valves about five running hours ago using the supplied feeler gauge. I'm on a relatively fresh gallon of fuel, open just a week or two with no change. I'm using Powermaster 15%. I'll change the glow plug next.


Bob

rajul

My Feedback: (58)

Bob, set your valve gaps to 0.002" and see if that helps too. The Saito gauge is about 0.004". When you re-assemble the intake manifold, try applying a thin layer of red high temp silicone on the outer surface of the manifold that goes into the cylinder to seal it, making sure none gets into the intake chamber.

Bone

Thank you Zombie [8D]