5. Engine

• Starting Point

• Metal Polishing

• Engine Rebuild Notes

• Before Starting
• Sources
• Miscellaneous
• Carburetters
• Engine Start !

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Starting Point

I am not going to list a blow by blow account of how I did my engine rebuild - the best source of information is one of the repair manuals available via eBay or an on-line bookstore on the internet. The one I like to use is the now out of print Haynes Suzuki 750, 3 Cylinder Models, Owners Workshop Manual (ISBN 85696 302 X). If you can't find one of these, the Clymer manual Suzuki 380-750cc Triples, 1972-1977 (Manual # M368) (ISBN 0-89287-285-3) is still in print - it just isn't as good as the Haynes manual - and if you do shop for the Clymer, the older ones from the 1980's include an additional chapter (chapter 9) which is missing from the more recent reprints, and which covers performance improvements, etc.. What I will do is highlight a few things to consider as you do your own rebuild.

Metal Polishing

I'm still waiting for a few parts to arrive and so have started to do a bit of metal polishing of the side covers while I'm waiting. The stator cover especially was in bad shape - I picked it up on eBay and contrary to the description, it actually was damaged. The seller adjusted the price, but I was still planning to replace it with a better one as soon as I could find one - you can see it to the left. As I hadn't really done any metal polishing before, I decided this would actually be a good candidate to experiment with. The lower edge of the cover had been hit hard enough to push the metal in slightly and the surface was badly gouged. I filed this down to get the shape back, then dremelled the surface with a coarse sanding drum, then hand sanded  the surface with 220 grit, followed by 400, then 1000 and 2000 wet and dry paper, then used black polishing compound with a buffing disc, followed by a bit of blue polishing compound. The end result is to the right. It actually turned out much better than I had expected, so now I think I'll keep it !

All in all, a couple of hours well spent - all I have to do now are the rest of the covers ...........

November Notes from the Engine Rebuild

First of all, I'm not a mechanic and as a result, these notes represent my personal opinions which may very well be incorrect – you are welcome to use any of this information, but you do so wholly at your own risk !

I've divided this into three areas: common damage and things to look for before starting, parts supply and related issues and lastly the important dealer notices, comments on the various manuals and a few 'miscellaneous' items. 

Things to check before starting

• First of all, in many cases these 2 cycle engines will be seized solid as there is so much exposed cylinder wall due to the port openings, which provide lots of surface area for moisture to enter and corrode the internals. I have had had some success at freeing stuck engines with putting penetrating oil in through the spark plug holes over several weeks, but not as often as I'd like. If it is seized due a mechanical failure, then the crankshaft will almost certainly need to be rebuilt and that together with the rebore, new oversize pistons (if you can find them - dealers do not have them anymore) , rings, gudgeon pins etc., will easily cost $1000+ in USD - probably closer to $2000 . If you are in Canada and sourcing NOS parts, then expect to pay even more as Suzuki dealer prices in Canada are roughly double what owners pay in the USA. Of course you can order parts from places like Dillon Brothers in the USA, but then you have the exchange rate, shipping and import costs to deal with. Depending on where you are located, a seized engine just may not be worth repairing.

• If the engine turns freely, then there are (at least) four areas worth looking at before spending too much money: 

• The exhaust bolt threads in the cylinder barrels are frequently damaged – these can be repaired with heli-coils, but specific to this engine, the previous owner had actually snapped off an Easy-Out in one of the bolt holes making it very difficult to do anything with it, and as well two other bolt holes had been badly stripped, so I ended up putting aside this set of  cylinders for this project, and using another set of cylinders with pistons that I had on hand. As it happens, the second set of cylinder barrels were also off a late model engine so it does have the raised porting which was a change made from the earlier models in the the later M, A and B models, although to be totally honest I just want the engine to run and so I personally don't really care whether the performance is as good as it could be.. 

• removal of broken off Easy-outs is possible so I may refurbish this set of cylinders in the future if I can find a local service here in Calgary similar to this one offered in the USA.

• The water pump shaft should be checked – if the owners used the Suzuki or Clymer manuals, they may have tried to follow the directions and pull out the pump shaft using pliers as described and possibly causing damage similar to what is shown in the photo. I have yet to successfully remove a water pump by just pulling on the shaft as the pump body is a very close fit in the lower crankcase half and it only takes a little bit of corrosion to really 'glue' it together. So far I've have only been able to remove the pump by spitting the crankcase and then gently tapping the pump shaft out from inside the transmission case as described in the Haynes manuals. This shaft shown below was unusable due to extensive previous 'plier' damage seen on the right hand end, and had to be replaced

• The original fitted chain was an endless link chain and many owners ran them till they just broke, This caused extensive damage under the left side engine cover – in some cases breaking the cover – and invariably took out the gear indicator switch. As this may also have done considerable damage to the upper and lower crankcase halves, it is worth checking whether these are salvageable before going too far. In any case, the needle roller bearing (09263-16006 or 09263-16012 fitted to the A and B models) that holds the end of the shifting cam often is often found filled with road grit, as it was difficult to clean properly when previously changing the gear indicator switch following chain damage, and it will either need to be well cleaned or replaced once the crankcase halves have been split..

• Most bikes will have been dropped at some point in their lives, and if dropped on the left side will possibly have damaged the side covers, the points mounting plate and the threads on the end of the breaker cam shaft. This is the half shaft that is driven from the starter clutch directly off the left end of the crankshaft. If this half shaft  is straight, then if you are lucky it can be cleaned up and rethreaded - otherwise it must be replaced. The other parts are available via eBay or possibly your dealer. As well, the tip of the side and centre stands are frequently bent or ground off as these drag easily on corners. The cover photo of the Clymer manual to the right actually shows the lean angle limit for these bikes quite well – in the photo, the left side of the centre stand can be seen to be just about to start dragging.. This is the older version of the Clymer manual which includes Chapter 9 (as indicated by the orange cloud in the upper right of the cover) which is missing from later editions. As the ISBN numbers are the same for both versions (which is a bit of a cheat when you think about it) , the only real way to tell is by checking the table of contents or the page count - the older copies were 165 pages, and the newer ones only 151 pages. 

Supplies and Refurbishment

• Gaskets and seals are available from several places, but even a dealer will often offer after market gasket sets which usually are provided by Athena p.l.c. in Italy. While the quality is fine, the actual sets themselves are a bit disappointing:

• The top end kit includes the required gaskets but does not include the three o-rings which are also needed for the base of the cylinders, to be fitted under the base gasket which they do include

• the 'full' gasket set does not include the o-ring needed for the drive shaft oil retainer plate, or for the gear shift indicator switch, and while it does include the small o-rings for the oil pump, it doesn't include any of the banjo bolt gaskets needed if you want to refurbish the connections on the oil distribution lines. As well, the o-ring supplied for the starter motor is thicker than the one fitted originally, making reassembly difficult .

• the oil seal kits available from dealers, and places like Parts n' More do not include the oil seal (09284-16002) that was fitted in the A and B models, and which goes on the the end of the shift cam shaft underneath the gear indicator switch, or the seal for the clutch rod.

• the water pump is supposedly not rebuildable, but most of the internal parts are available either as original Suzuki parts as they were used on the RE5, or in after market kits. I bought mine from Erik Potze, but he recently advised me he was no longer carrying them – you can still order water pump parts from GTReimer in Germany - just send him an email and ask about kit number 17010-31099-000-Z. A photo of the disassembled GT750 water pump is shown below.

• The water pump repair kits include, referring to the photo above from left to right, the bearing, the oil seal, the two large o-rings located on the holder set for the pump driven shaft, either a carbon faced seal or a Teflon seal (if it is an after market kit), the small o-ring, the drive pin, the large circlip and the small circlip. Also included,but not shown are the banjo bolt washers for the drain line that runs from the top of the water pump housing through to the area of the water pump cover inside the transmission case. If the bellows (fourth from left, lower row), the seal seat ( sixth from left, lower row) or other parts are damaged then, if GTReiner can't help you, new water pumps are still available for purchase from your local friendly Suzuki dealer for about $180 USD if you live in the USA, and for much more than that if you live elsewhere.

• the bellows (seen fourth from left on the lower row) are not available as a separate part number, and if the spring is damaged, then you will need to buy a new pump, or recycle from a spare. Also note that the carbon seat (seen fifth from left on the lower row) is quite fragile and can be broken easily. The Teflon replacement I had was lacking the two small locator grooves required for it to sit properly on the bellows when the pump is assembled and the large circlip is installed. I used a small file to make the modification

• the oil seal seen second from the left is just a standard 10 x 22 x 8 ARS oil seal, and the bearing is Suzuki part number 08113-62000 and is still available from Suzuki dealers for about $6 USD in the USA - this is a NACHI 6200 series bearing, and there is a good reference chart available here which shows various bearings available from third parties, as well as cross references to different bearing manufacturers. 

• The white nylon water pump driven gear will almost certainly be cracked. though the centre bush as seen in the photo to the right. While this gear has not been available from dealers for quite some time, these can still be purchased via eBay, GTReimer and other sources, so for the moment at least I replace them. Eventually of course, as the supply dries up this will not be possible so other alternatives will need to be looked at - one option is to repair these gears and a set of instructions for doing this are available from Lane Pipkin at the  Kawasaki Triple Site  where you can contact him directly (you will first need to register on the site). I have looked at having a new gear made (GTReimer actually did sell alloy replacement water pump drive gears at one time) but currently the cost is still much higher than just buying an NOS part, so as yet it is not economical - this will change over time. The last two that I've bought were about $60 USD each, and both came from the UK.

Additions, Changes and Miscellaneous

• Crankcase colour codes - if you are having to mix and match gears in the transmission or have had to change out a crankcase half due to damage, then you need to be aware of the colour coding used by Suzuki to manage backlash in the gear train. The 1st and 2nd driven gears and the kick start drive gear are matched to the paint codes found under the clutch plate basket on the lower crankcase half on the right side. This information is also covered in detail in the service bulletin number GT-29 issued May 1, 1975 and revised December 19, 1975 

•  Cylinder locator bolts - corrosion will generally 'weld' the cylinder barrels to the upper crankcase half. So far, I've been lucky and found that several weeks of soaking in good quality penetrating oil has been enough to eventually soften things up enough that the barrels can be worked loose, but that will not always be the case. Fred - our local GT expert - made a pull plate that is attached in place of the cylinder head, and which allows you to slowly pull the barrels up off the studs, after which you would probably need to replace the studs. If anyone is interested in more detail or a photo, I can relay an email to him. You can also refer to Suzuki service bulletin GT-25 issued August 15, 1975 (found here or here) which describes another method using a 'puller kit' (part number 99104-03100) - as I doubt this is still available from anywhere, you can create you own kit fairly easily - just read through the service note for the details. In any case, when reassembling, I coat the studs with white grease to hopefully slow down the rate of future corrosion.

• the Clymer manual as well as the Suzuki service manual talk about using emery paper to clean up the pistons and other areas (page 38), and the Haynes manual expressly says not to, which I'd agree with. The aluminium alloy is soft enough that particles from the emery paper could embed themselves in the surface of the piston which would not be good. I use a 3M Scotch pad soaked in a light solvent on the basis that if any particles should remain they will burn off.

• while large sections of the Clymer manual are lifted almost verbatim from the Suzuki shop manual (presumably they had an agreement of some sort allowing them to use the material) they sometimes fail to include information that would be useful - an example would be the reassembly instructions for the clutch assembly on page 46 and diagram 76 where they don't give information on which way the chamfer needs to go on the two large thrust washers. Due to the way the crankcase is machined, the inside washer has the chamfer facing inwards, and the second washer has the chamfer facing outwards as described on page 57 of the Haynes manual. This is mentioned in the Suzuki service manual also, but unfortunately without any real detail, other than to say its important ! They do provide a diagram in which you can just make out the correct positioning as shown below.

• The Suzuki and Clymer manuals list the NGK B7ES plugs as standard, however this was only true for the early models (J, K and L) - for later models the standard plug was actually the NGK B8ES which was one heat range cooler

Carburetters

December 29 update

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