My first SRX rebuild.

[Martin Giddings]

Am about to do a total rebuild of my 1985 Jap Import SRX 6. I want to recon all moving parts if needed, are there any tips you can give, I've never done an SRX before. It had a bit of rust and a base gasket oil leak when I took it off the road. I am painting first and while I am doing it I want to acquire engine info. I only want to use it on the road and would like it to last me another 22 years so I want to get it right.

[bikeseamus]

     The SRX/XT 600 engine is a durable unit.  A few questions... 1. How many miles on it?    2. Did it burn oil and lose compression? 3.  Building the engine for longevity seems to be your primary concern... correct?  No point in replacing good parts or adding performance parts that will make it less durable. Many ways to approach this.

[Martin Giddings]

Bikeseamus, it wasn't burning oil, and it has 35,000 on the clock 30 of which were in kilometers (I put a speedo converter on). It rattled a lot from the time I bought it but I have never heard a mint one to know what it should sound like (maybe a run with you guys on my SR125 would help solve that one).
I have bought a Pedator exhaust as the original downpipes were rotting, so I imagine there may be some upjetting required, along with a highflow filter. Apart from that, I may play with sprocket sizes for better top end, but will be going for standard engine stuff (depending on wear I may have to go up a piston size).
At present the engine is in one peice (on my garage floor-oil as well-in the engine) while the frame is in my sitting room being de-rusted/primed. Thats what I call "housework" though the Missus disagrees (what does she know).
Any help you can give me will be of use. So far I have ascertained that an new oil pump would be wise.
Thanks in advance.
Martin
 

[Steve H]

At 35,000 miles I would expect 5th gear to be fairly well pitted. If the rattling clears after its warm then its piston slap, so a rebore is in order, as bikesaumaus says its probabaly best to stick with the standard compression ratio, and if the wallet can stretch to it a Yamaha piston. Little end may also be worn, which can be more expensive dependant upon how you decide to fix it.
Flywheels can be a pig to get off, remove it BEFORE stripping the top end, the best approach is to use an air gun, other than that they come apart relatively easily.

[Martin Giddings]

Thanks for your help. Will be making a pictoral diary of the job, I will post it here, when done. That may be a while, I am on a low budget, house husbandry doesn't pay well! The SRX isn't exactly top of the Missus shopping lists (and she has quite a few of those).   

[bikeseamus]

Martin

  Crankshaft assembly is something that takes care and experience to conduct properly, and is vitally important to get right, so find out who the goodguys are in your area and let them handle the crank and case reassembly. Cam timing is straightforward and important, as is a good valve job. A five angle seat cut is better than a three angle cut because it flows better, and a stock compression ratio will keep the heat down and make for a longer lasting more user friendly kick starter.
    You will have fun and learn quite a bit, but it behooves you to find a competent experienced engine builder to help you the first time. No one is born with this knowledge, and you can't read too much about it or learn too much. Good luck.

[peterj]

A few thoughts. If money is limited, I would condsider limiting the amount of mechanical work to what is needed right now.

If it wasn't burning any oil it doesn't sound to me like it needs a rebore yet. They are pretty mechanically noisy, something which is magnified if like mine, someone has removed all the rubber fin packing pieces.

Whilst I'd agree that there is a high probability that 5th gear has some wear, if it wasn't noisy and you don't have to pull it apart for any other reason I'd put that down the priority list. If you decide to do it yourself, you need a 10 ton press and a good quality bearing puller or similar to exert pressure under the gear to pop it off.

You can remove the barrel and head in one piece to do the base gasket - saves replacing a good head gasket. Just be very careful reseating the cam chain guides.

I wouldn't change the oil pump as a matter of course, only if it doesn't measure up to the wear limits or is obviously scored etc.

If the small end is worn (and make sure it's not the gudgeon pin if there's play - it was on mine), in situ reaming and bushing (see Steve's advice above) sounds like a sensible option as long as you are not trying to build a high revving performance motor.

The cases on mine split and went together again very easily without needing any of the pullers (the ones for splitting/reasembling the cases that is) listed in the manual. It was a 40C day though so I'd suggest turning up the heating while you do those bits if you don't farm out that part. Yours might need the pullers etc, mine may have been an abberation.

Since the 1JK has an oil cooler as standard, I wouldn't worry about a tad more compression if you do want to change the piston. If the cam needs changed for other reasons (wear/scoring), getting a nice one designed to match a HC piston can cost less than standard bits and provide a sweeter motor than stock. Mine runs 11.5:1 with a specifically designed long duration cam and kicks nice and easy. Absolutely nothing wrong with leaving everything standard though.

If you need a new drive chain, buy a recognised brand name. Singles don't put out much HP, but they absolutely trash cheap chains.

Have fun, and don't get discouraged when it's all in bits and it starts to feel all too much. Every rebuild I've ever done has got to that stage at one point or another.