peterb

Hi Ian in China, I've run three PRO 300's with Keihin and find the best set up, for me, as follows: 128 main (I used a 125 reamed out to this size) 40 pilot GJH needle Bike runs bril. Bye, PeterB.

Hi sunny, All that stuff what everyone else said and this bit more: Usually 1 bearing race either side on the 159, I always use C3 - higher clearence bearings in the crank case, don't cost much more than a std bearing. Definately no sealed bearings here. You need to heat up the crank case bearing housings either with a hot air gun, or even boiling water to fit in the bearing so as not to use brute force. I usually place the bearing in a freezer to contract it a little. Try to use hi temp viton oil seals for the crank case, I can't remember now but I think the older Gas Gas motor uses a similar sized viton seal for the crank case and may be readily available in your area P/N M01217001, 25x40x8 (the bikes up to 2002) - check it out with your manuals. Just out of interest, I run a roller bearing on the clutch side of my Bult with a ball race on the other side, I reckon the roller takes more axial load. Bye, PeterB.

Hi cope, That's interesting, I often wondered about the plated narrow rings on the S3 pistons on Gas Gas running in a nicasil bore, if they need to be replaced more often that the CI dykes rings on earlier motors, which just keep on going and going, hmmmmmm. Bye, PeterB.

Hi PaulB, That 500 Triumph of yours is one of the best looking Triumphs I have seen. I had a road going Tiger 100SS for 5 years when in Yorkshire in the 70's, such a lovely motor I thought it would have made a great trials bike save for the weight. Good to see such fine efforts going on. Bye, PeterB.

Hi Brian, I was thinking about your bike as I was in the shed, fettling the Beesa. You can use a 250 Bultaco crank (or better still a 325), but needs the 325 rod as the little end is bigger. I don't know if the Italjet will fit, measure it up, same stroke? I don't know if the Italjet has the same taper for the mag (wouldn't think so) and if the Bult sprocket and weights could be adapted to fit the Italjet crank. Another semi useful thought to get you going and not have to machine anything or ruin any parts, you could drop out the sleeve from the barrel (upside down over a ceramic plant pot in the oven when your wife is out), then machine up a 2mm thick spacer to slot inbetween the liner and barrel, like a big washer and re-fit in the oven. This theoretically provides you with the correct port heights and piston crown height without having to machine any original parts. Although the liner and cylinder ports would mismatch, it shouldn't affect performance too much. Alternatively, make up a base spacer - actually this is much heasier and gives the same results as above. Or get hold of an Alpina cylinder and head. Bye, PeterB.

Hi de ho there Tim, Will give you a call soon. tis not Tony the copper, but someone much closer to home. Ta ta, PeterB.

Hi Neo, It's the same for me, don't care for working on car's at all and really enjoy the bikes. I'd still put in a new seal though! I guess you'll use an adaptor in the spark plug hole, block off exhaust and inlet and use a vacuum pump with vac pressure gauge tee'd in. Clav3 - that's a huge amount of wear after a year, are they dykes type rings (L-section) or plain. Bye, PeterB.

Hi MJB, The 05 Raga may have been the first 300 Raga, it didn't have gold triple clamps as far as I remember. Keihin carb allows the motor to rev highr, it is a smoother carb than the DellOrto 26 PHBL but does provide any extra punch, not sure if the 05 had Ohlins too, good shock though top bush wears quickly. Bike is great with a Hebo flywheel weight (750 gm). I'm on my second 300 Raga, brilliant bike, definate, noticable motor improvement in 2008 model from previous years. Hard starting on older 300's due to Ducati ign, needs pick up sensor moving closer in to the flywheel to approx 0.1mm air gap for improved hot start. I use 10T/42T for the older models gearing, std is a bit fast for me going up slippy creeks/becks/streams/burns. Bye, PeterB.

Hi Kurt, The pick-up to flywheel clearence info is there only for Ducati ign systems, I am pretty sure your year model has a Kokusan ign system. If you must use a torque wrench, then go for 40Nm, the bolt is only 10mm dia, not like the much larger nuts found on other motor cranks. To loosen the pick up sensor, use a correct size spanner (5 or 6mm, can't remember but I have one in my bike tool box), may come loose with pliers. There is a little slack on the mounting holes to position the sensor accordingly. That 30 x 10 tube - I don't know! I have one too. Bye, PeterB.

Hi Brian, I wonder if at some stage a previous owner has fitted a crankshaft, or complete engine from an Alpina. These had a 64mm stroke, and would account for you having the Mahle piston extend further out of your barrel than it should. My own Bultaco has a 64mm stroke Alpina crankshaft with Sherpa gear cluster and Alpina barrel. I have a few very old stock, but new Mahle pistons for the 325 Sherpa and will measure them up over the weekend, will also measure the old Alpina piston port heights. With the crank pin re-located to achieve the 64mm stroke, there would be a change of 2mm up and 2mm down in the stroke when compared to a 60mm stroke Sherpa. Bye, PeterB.

I would have just put a new seal in and be done with it, can't be more than a few dollars. Bye, PeterB.

Hi brt650, this is an interesting thread, The original piston for a 325 Bultaco was a Mahle, I think it was 83.2mm diameter. I have not seen replacement pistons from these times so cannot comment as to how they fit in. Seems a bit much to machine out the head to fit a piston, not quite the norm. Are you sure the skirt heights match for inlet and ex timing, are the transfer cut aways matched for height and width. From what you write, it appears the piston crown height is too tall for your bike, I guess it is too late to reconsider using another type of piston. I don't think the difference between a forged and cast piston is going to affect the thermal expansion properties of the piston material - does anyone know about this? I gather that for casting aluminium, a grade to LM4 is normally used, may be the same for forging. It is normal for a 2T piston height at TDC to have the piston crown flush with the top of the barrel, that is the shouldered edge of the piston. Good luck, PeterB.

Hi bowershall, Try one of the Scottish GG dealers, or White Bros in Darlington. But.....why do you need a new carb, they usually last for years. Try the classifieds as there may be a rider who has fitted a Keihin carb and has their old DellOrto for sale. Bye, PeterB.

Hi scotty, Here I am! Your cross references are fine, I just measured up an old brg with a vernier to get nominal sizes 17x40x14. Bye, PeterB.

Hi Matt, The sub frame will fit your 160 if it is from a 1994 bike, a 95 sub frame looks the same but has a different fitting to the main frame. Bye, PeterB.

Hi Neo, I still reckon it is the mag side oil seal. Symptoms lead to this. Have you replaced this? Yes, I see that you have pressure tested the cylinder/crankcase area, but, when these seals leak they allow air to enter the crank case under vacuum, not under a positive pressure. I don't think that a pressure test would always show up a leaking crank case oil seal as we are dealing with vacuum, rather than positive pressure. I would say that a positive pressure on the inside (Spring lipped area) of an oil seal would provide a tighter seal to the shaft. Well, that's my theory for now. Bye, PeterB.

Hi penno, The RHS cable operated brake never worked that well on the Bult, and the gear lever on the left was just plain awful, it hangs way too low. But, if you must have a LHS gear change and RHS brake then try as Nigel advises or Sammy Millers. Bye, PeterB.

Hi Neo, Maybe I should have a read a little further! I guess you still have the same problem then, if it were me, then I'd strip the motor and check for the possibility of a leaking crank case gasket, or maybe a pinhole in the crankcase (had one on a Fantic 301 once) I couldn't stand riding a bike that didn't run properly. Hopefully something would show up. Good luck with this one, PeterB.

Hi Neo, I started reading this thread today and got to page 3 and decided to see what the eventual fix was, hopefully on page 6 - there isn't one! Are you still having problems? Somewhere early on in the thread there are a few photos of your Keihin, these show the vent pipes going up and then down. I've never known a bike to run well with this set up as there cannot be any self drain facility from either vent due to an approx 25-30mm of extra height the fuel must travel before it can drain. The top of the float bowl must be vented to atmospheric pressure to allow the carb to work properly. Just to check this and to rule out this possibility, have you tried removing the vent hoses? Also, the float bowl drain should only run downwards. If this is ok then have a look at replacing the mag side crank oil seal, not an expensive job to do and worth trying out to rule out this likely possibility. I guess by now you have fitted an inline fuel filter. I've ran Keihins on Gas Gas since 2001, only problems have been with not fitting an inline filter and making sure there are no splits in the inlet hose. Have always ran faultless otherwise. Best needle for me on 300 PRO's and 321 GG has been a GJH, the recommended JJH runs a little quick at the low end. Bye, PeterB.

Hi Matt, You can post the frame number on here, it should start with "VTR GG*************" or similar. This will give the year and motor size of the bike. Excuse me for writing this but I am a teacher and can't help it (sorry) Start every new sentence with a capital letter (Use the shift key), write about yourself as "I" - capital letter. Names start with a capital letter. I think that's enough for a start, just trying to help. Bye, PeterB.

Hi Sam, If you have a bit of time, you can carefully peel back the outer casing of the fan motor, usually in two cylindrical pieces pressed together. The std Jap fan motor works well, the older ones used to sever the windings where they are wound tight over part of the rotor assy. Check for broken wires, you need a magnifying glass. If any broken, use a scalpel to scrape of the insulation and solder up the wires. It will work 100% again. Takes a while to fix but at no dollar cost (I would just put a new one on these days) Bye, PeterB.

Hi Matt, Re-fill with a 10 weight mineral oil, not synthetic, or an ATF (Automatic Transmission Fluid) rated to Dexron III, 700 ml. Bye, PeterB.

Hi Kurt, Lots of questions. If you have the flywheel off, then remove the stator and grease the end of the crank shaft, prevents it from getting rusty down the track. The flywheel to crankshaft tapers offer a very tight fit, the nut/bolt at the end of the crank should be reasonably tight, I don't use any torque figures, prefer going by feel. Pretty sure the pitch of the puller thread is 1.0mm. If you want to adjust the static timing, you can slot the pick up sensor holes to provide a good range of adjustment, on the 300 I find the timing spot on. Put your own marks on the flywheel for strobing if you must. Bye, PeterB.

Yes! (This has to be my shortest answer ever) Bye, PeterB.

Hi scotty, These are not the same as the PRO head stock bearings, they are taper roller but a smaller size than the PRO. Look for an equivalent to HIC LM117 49/10. Pack with a water proof grease like Mobil HP or similar. Bye, PeterB.