Topic: Bringing a 750 K1 back to life

[Laids]

What a great project! Also, the picture in the gigantic shop, I'm jealous.
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Well the snowmobile season is officially over here in Southern Ontario...

What snow machine do you have?     I rode a buddies El Tigre years ago, that thing was fast! 

2017 Skidoo renegade 600 and 2015 1200 4 stroke, buddys are riding new stuff, 900 turbos etc

[Laids]

Engine is back together. The spare parts that came with the bike included 2 complete gasket sets, a 76F engine and new  stock Honda rings. The rings were 392 but as far as I can tell they fit the 300 pistons. I was tempted to use the 392 pistons as they were nice and clean. The difference to the 300 pistons is noticeable with a much larger chamfer at the top edge. I decided though to use the original pistons to keep it original. The 392 rings had the 3 piece oil rings, I read some have had issues with installation so I was a little concerned. I found if the Centre ring goes on first the other 2 scrapers fit fine. Cylinders were honed and checked ring gaps, a few were a somewhat wide but I thought good enough, I know others here might have more stricter tolerances.
Other than the usual chain tensioner flopping back a few times and backing off everything went smooth. Torquing down the head it started to pull the studs out on about half the studs before reaching values. I left it overnight and not knowing what to expect went back at it the next day. Everything torqued up fine after that.
The valves and seats were lapped and went back to their original locations. As per my last engine , forgot the valve seals, only had to redo 4 this time though. Top end went together with no helicoils necessary.
Starting on the carbs next, number one carb is the worst. I’m thinking the bike must have been on a side stand for while full off gas to be this grotty while the others were fairly clean. When I inspected that float  found a hole .

[BenelliSEI]

That’s one heck of a hole!

[newday777]

I have a brass float if you need a replacement

[Laids]

I have a brass float if you need a replacement

Thanks but one of the other brass floats is dented, so would need 2. I have a set of single pull carbs but am reluctant to steal from them. I have quite a few plastic floats so will use plastic, not sure if combining brass and plastic would be a good idea. I couldn’t find any brass floats on line, I guess they have been replaced with plastic.

[newday777]

You probably shouldn't mix them, just replace them all with the plastic.

[BenelliSEI]

Truthfully, I’m running one plastic with three brass in my K1 (emergency fix that never got corrected) and it doesn’t seem to hurt…..

[HondaMan]

The brass floats will make the float-bowl level slightly 'deeper' than with the plastic ones, about 1mm difference is all.
The plastic floats came about to help stop side-stand-piddling on hot days, and later became the cheaper ones to make, during the K2 era.
(For performance buffs: use brass if you can, they tend to keep the bowls deeper while riding, compared to plastic ones.)

[Laids]

The brass floats will make the float-bowl level slightly 'deeper' than with the plastic ones, about 1mm difference is all.
The plastic floats came about to help stop side-stand-piddling on hot days, and later became the cheaper ones to make, during the K2 era.
(For performance buffs: use brass if you can, they tend to keep the bowls deeper while riding, compared to plastic ones.)

Good to know

[MauiK3]

Not sure I understand why they make a difference, is it the weight making them react differently to changing bowl depth?

[HondaMan]

Not sure I understand why they make a difference, is it the weight making them react differently to changing bowl depth?

It's the material: the brass ones are lighter than the plastic ones and react in a more lively way while bumping along on the pavement. They result in actual float levels slightly higher while riding, but lower or the same as plastic when sitting still. The US DOT leaned on Honda in 1971 about this issue, trying to say that the deeper-while-rolling was making the bikes emit more pollution. Since it's a 'political' sort of thing I haven't talked much about it in these forums 'cuz we're not supposed to get 'political'. But it IS the truth, so there is that edge to it...I made note of this in several places in my upcoming book, which caused no end of grief for Honda in the CB500/CB550 carbs.

[Laids]

Moving forward, the carbs are basically together, just waiting for needles and seats. I have a bunch of extra plastic floats so picked out the best ones. I finally bought a ultra sonic cleaner last year, always borrowed a friend’s until he moved away. It’s a 22 litre, really didn’t have to be that big but it seems to do a good job. Can easily get a rack in with room to spare. I have used the extreme Simple Green for aircraft, mixed with water, after use poured into a 5 gallon bucket and use again until too dirty.
The oil pump was next. I’ve done about 4 in the last 4 years, but I have never been able to get one completely apart, only the 2 springs and seals. I usually can get some of the JIS screws out but not all. Maybe there’s a trick, so far I give up after checking the gear to feel some resistance then think ‘good enough’.
Next is the front brakes.

[BenelliSEI]

Looking good, lots to do!

[MauiK3]

Good progress