tortron Posted November 23, 2022 Author Share Posted November 23, 2022 Here's a 212cc build, using an lt160 rod, 7mm offset crankpin, Thailand piston I think I will weld up a crank and fit an lt160 conrod offset as much as is suitable, and run one of my flat Honda pistons. This will take it to 180ccish depending on how things fit. Compression ratio would be alright too, and lots of room for valves 6 Quote Link to comment Share on other sites More sharing options...
tortron Posted November 23, 2022 Author Share Posted November 23, 2022 Very interesting is the suzuki raider r150. Which has a 62mm piston stock and has endless tuning options, big pistons in every shape, conrods in every length, and crank pins in what ever offset you like. If I bore the gn/dr crank pin out from 28 to 30mm I would then have almost endless options, including "blank" topped pistons which are extra thick so you can mod them however you like. The con rods look like they are around the lt160 length +/- some mm either way depending what you want. Good for stroker build The only issue is I have not figured out how to get something from the Philippines sent here, but I think this is what I'm going to look into 1 Quote Link to comment Share on other sites More sharing options...
datlow Posted November 23, 2022 Share Posted November 23, 2022 There's a few Philly moped enthusiasts on mopednz I also work with a few Phillys so could attempt through them 1 Quote Link to comment Share on other sites More sharing options...
tortron Posted November 28, 2022 Author Share Posted November 28, 2022 I'm told raider has a 16mm piston pin, so I will delve deeper and see what might work 1 Quote Link to comment Share on other sites More sharing options...
anglia4 Posted November 28, 2022 Share Posted November 28, 2022 Raider is basically an FXR 150 is it not? There will be truck loads of info around on FXR stuff in Bucket Racing circles. Ask some questions on the bucket page on Kiwibiker maybe? Quote Link to comment Share on other sites More sharing options...
tortron Posted November 28, 2022 Author Share Posted November 28, 2022 Almost had engine buttoned up, had just filled with oil and set the valve clearances. Then the intake valve started sticking open So I took the head back off Guide snapped at the retainer. Hmmm Was probably damaged and waiting to ping off, the valve that was in it had lost its retainer end and dropped and bent. Lucky that it happened before the engine was running 1 Quote Link to comment Share on other sites More sharing options...
tortron Posted December 14, 2022 Author Share Posted December 14, 2022 Honestly, not expecting to find this Entire brush end of the starter totally blown to bits. Cam chain had jumped off the crank at some point during the lock up, and had bound up the starter gear. The wire has sheared and looks like the starter made a 1/3 turn. I'm not sure how this could happen when the crank is stopped Something like, valve drops, engine locks, shock sends through the starter gear and reduction gear, somehow causing the starter to blow to bits, and the final stretch of the timing chain rotated the armature a bit. Crank seems fine tho, just some scuffing on the starter bendix gear where the cam chain jammed it, no damage to the casing where the reduction gear run. No glitter or gear teeth fell out of thr engine, have had both sides off to see what's up, plastic oil pump gear looks fine, nothing in the sump mesh either. And have turned over by hand in gear incase I could feel or hear anything without splitting the cases A Christmas miracle happened and I got new valves, guides, and a reamer in a couple weeks, so the dr125 head is back together and all installed, put a replacement starter in and it turns over fine. Exhaust and carb back on tomorrow and will see if there's any terrible noises. 6 Quote Link to comment Share on other sites More sharing options...
Mop Head Posted December 20, 2022 Share Posted December 20, 2022 I still have an FX125 motor (I think) I would donate to this cause. Was running when pulled. DOHC etc etc. Quote Link to comment Share on other sites More sharing options...
tortron Posted December 21, 2022 Author Share Posted December 21, 2022 On 20/12/2022 at 16:47, Mop Head said: I still have an FX125 motor (I think) I would donate to this cause. Was running when pulled. DOHC etc etc. Oh yeah, that could be worth inspecting. Even a stock rod coupled with a slight offset pin would gain a few cc. Here's a "big sump" GN? 125 engine 1100 ml oil vs 850ml of the normal GN125 engines. All the covers, cylinder, and head are visibly different. I dunno what this was from, but I have a suspicion that it is the engine that takes the high dome big bore piston (and probably the different pitch timing chain and conrod) 2 Quote Link to comment Share on other sites More sharing options...
SOHC Posted December 22, 2022 Share Posted December 22, 2022 How do you line that crank pin up? Quote Link to comment Share on other sites More sharing options...
tortron Posted December 22, 2022 Author Share Posted December 22, 2022 1 hour ago, SOHC said: How do you line that crank pin up? By eye, then hammer it home from what I have seen of the builds on YouTube (hold it with your bare feet so it doesn't move around) I'd probably rig something up with v blocks and a surface plate I guess 1 Quote Link to comment Share on other sites More sharing options...
keltik Posted December 22, 2022 Share Posted December 22, 2022 GNs weren't made to handle that kind of precision. If there's no fag ash and sand in your crankcase, you're doing it wrong. Quote Link to comment Share on other sites More sharing options...
tortron Posted December 22, 2022 Author Share Posted December 22, 2022 Posibly a gz125 engine Or volty Quote Link to comment Share on other sites More sharing options...
SOHC Posted December 22, 2022 Share Posted December 22, 2022 3 hours ago, tortron said: By eye, then hammer it home from what I have seen of the builds on YouTube (hold it with your bare feet so it doesn't move around) I'd probably rig something up with v blocks and a surface plate I guess Yes I was just watching them hammer cranks together and then wack a big steel wege in to separate it to get the rod to move Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted December 22, 2022 Share Posted December 22, 2022 4 hours ago, tortron said: By eye, then hammer it home from what I have seen of the builds on YouTube (hold it with your bare feet so it doesn't move around) I'd probably rig something up with v blocks and a surface plate I guess Was chatting about assembly of Aprilia rs250 cranks yesterday. A guy bought two of them NEW and he said you could see the misalignment by eye. he tapped them around with a hammer to get them straight. Doesn't sound right to me but what do I know. Quote Link to comment Share on other sites More sharing options...
tortron Posted December 22, 2022 Author Share Posted December 22, 2022 Yeah that's how you do it. Spin in a lathe and look for wobble 1 Quote Link to comment Share on other sites More sharing options...
tortron Posted February 14, 2023 Author Share Posted February 14, 2023 Dug out a mikuni flat slide pumper from my early dr200 parts Tm28 It's 99% there, can make it work with some other spares I have. (failing this il get an aliexpress version, which appear to be shorter whichmay be useful) I expect big gains from changing thr carb. The Bs26 is pretty average Quote Link to comment Share on other sites More sharing options...
tortron Posted March 12, 2023 Author Share Posted March 12, 2023 Finally took the GN out for a test in its current setup Dr125 head, with double valve springs 150 kit, with valve cutouts in piston Hotcams cam 2 base gaskets Standard exhaust and GN bs carb setup from how I always had it Pretty eh, I expected that due to the low compression of the combustion chamber and lame 150 kit piston It has more power than a stock GN but it feels kind of sluggish off the line, has a bit of a stable between 6 to 8k rpm Really gets on cam at about 9000rpm and pulls to???? Rpm where it will sit but not give any more (my modded tach and the hour meter tach I don't trust much, modded says about 10 and never goes higher but the rpm sounds like it goes higher, hour meter about 12k but is inconsistent, I might have to make a light weight custom cluster) Anyways its good at high rpm, probably cos of the big valves coupled with the cam. I think I could tune the stumble out and help the low end with a vm or tm carb. But I just dislike this piston, and don't think it's worth any further development using it. Plan now, go back to 125cc. I'm going to run a complete dr125 topend, so just a stock jug with a high dome piston in it. This will give a good compression ratio, should put out a bit more power with the bigger valves, and along with the Hotcam will be a nice package. Then I'm going to throw a better carb on it, which again should improve it all over. 7 Quote Link to comment Share on other sites More sharing options...
tortron Posted March 12, 2023 Author Share Posted March 12, 2023 Can get a stock or +1mm 11:1 piston for the dr125, about the same price as a China bigbore kit Longer term I'm going to look at how big of valves I can put in the GN head. If I could run at minimum, dr125 valves along with a big flat top Honda piston, I think that would be pretty good. Would need machining to fit the DR valve springs. may be touch and go as there's different angles involved. I'm sure I have at least one head I can try it on. Can do about 165cc with the piston I have, but really want those bigger valves Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted March 12, 2023 Share Posted March 12, 2023 why dont you try raise compression? Quote Link to comment Share on other sites More sharing options...
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