Re: Rebuilding Suzuki\'s 1.3/1.6
Not really a problem specific to 1 and 4, probably just co-incidence.
The seat finishing of some engines leaves a lot to be desired, some are awful and consequently coke up the affected valves.
I assume you have removed the valves to fit new seals, if you clean the valve throats of the "bad" cyl.'s you'll find the seat inserts are causing an undercut area below the seat. during the overlap period, inlet valves act as exhaust valves and let a small amount of contaminated gas into the inlet port, ordinarily this would be drawn back into the chamber during the intake phase. The undercut causes the intake charge to stall at low valve lift, just when the intake valve is at it's coldest, at this point the hot carbon in the cont. mix. lands on the back of the valve and is baked on in the overlap period, when the whole cycle begins again.
The best thing to do is remove the undercut using a mounted point in a power drill, flexi drive, Dremel or similar. Not as scary or hard as it sounds, it's actually very easy, just take your time and smooth the under cut out, making the area slightly concave doesn't really matter as long as it's smooth. Stay away from the top edge and the seat area itself, concentrate on the lower 5 mm. Do all the valves, even the good ones, doesn't upset the mixture and improves response.
All the Suzuki alloy engines are sleeved.
Watch when you replace the oil seals on the crank and cam, some of them can get grooves worn in them, just trial fit the housings and position the seal ring in a "new" place to get the best seal. Fitting a new seal to the "old groove" can sometimes, but not always, result in it tearing or leaking.
Take a look at the file to see a reprofiled valve throat
Any problems e-mail me direct.