tyjay Posted March 17, 2013 Report Share Posted March 17, 2013 Hi guys ,can I have advice my stock ty175 motor seems flat and fed up of resetting the points ect and I've thought of buying a set of boysen reads lifting the flywheel electronic ignition I want to up the compression slightly I've heard you can purchase a thinner was gasket but I'm not sure which one and where to get it from other option was to skim head but how much should I skim and finish te bike of with a wes system exhaust would I gain from them mods to make the Bike More responsive and better to ride ? Quote Link to comment Share on other sites More sharing options...
guy53 Posted March 17, 2013 Report Share Posted March 17, 2013 I don't know about the 175 but on my 250 A or B I replace the head gasket ( very thick copper ) by a thin aluminium ( about .005 '' ) to increase the compression. Guy Quote Link to comment Share on other sites More sharing options...
tyjay Posted March 17, 2013 Author Report Share Posted March 17, 2013 Was wondering where to get them thin gaskets from tho has any one got any ideas ? Quote Link to comment Share on other sites More sharing options...
bestrcpilot Posted March 17, 2013 Report Share Posted March 17, 2013 The thinner head gasket is something that has to be made. I used sheet cooper from a model airplane shop. The sheet cooper can be easily cut with a pair of scissors. There are threads that explain the mods that can be done to the ty175 engine, the best mod that I fine that works the best is a new carby. A 40 year old carby is worn out and will never work right. I put a 24mm Mikuni flat slide on mine and it turned a dog into a jewel. Quote Link to comment Share on other sites More sharing options...
andy.t Posted March 17, 2013 Report Share Posted March 17, 2013 The thin gasket you mentioned are often in the gasket sets, I think but not sure that the thick one was an original from Yamaha. The standard 175 should run fine with plenty of power but as time goes by like all bikes it will start to fade. There are a few things that can compromise the performance even on a rebuilt engine, as you mentioned fitting new reed valves like Boyesen reeds will help if the old ones have work hardened and do not flex as well as they should. If you do fit them try going up on the pilot jet to 27.5 or even 30 and re adjust the mixture screw. If the ignition is not set correct as you mention then that's another thing that will not help. I have the electronic ignition that Trail and Trial sells and its never let me down. Hopefully the engine is in good general order, getting few performance parts will help . I will say that after I rebuilt my 175 it was a bit flat and I tried fitting several parts to improve it..all the parts helped a bit on the way...new carb...new reed block and boyesen reeds and bigger pilot...air filter box mod....boost bottle (cant wait to hear any reply on that one...again) Electronic ignition. I have the thicker gasket fitted on mine, never bothered with the thin one that I got in my gasket set as the bike runs fine with the thick one. Hope this helps Quote Link to comment Share on other sites More sharing options...
tyjay Posted March 17, 2013 Author Report Share Posted March 17, 2013 When you say boost bootle what do u mean and what is the air box mod and do u recommend any websites to get it from and what's the current point gap for ignition I race classic minis n set them to the same gap as that and it starts fine ect it's had new piston n and rings ect when I rebuilt but like you said it seems flat not sure if it because I've been on my bros Armstrong 250 to much ! But boysen reads and a new pilot jet ill probs do lighten flywheel I can do for nothing as I have access to machine I've bought a bearing to fix the sloppy gear selector and il look for a new head gasket but any recommendations from where to buy the parts from Quote Link to comment Share on other sites More sharing options...
bestrcpilot Posted March 17, 2013 Report Share Posted March 17, 2013 The book calls for a point gap of .020 inch. But I just use that setting as a starting point. I set the the timing so that the points open at .090" before top dead center and not at the book spec of .070" and the only way to do this is to play with point gap as the stock stotor can not be moved. New reeds will help as will a spacer plate between the reed block and the rubber intake boot. Just make sure the reeds are closing down tight to the reed block. a intake rubber from a Yamaha rd350 also as it centers the carb to the reed block and is not offset to the left like the stock intake. Here in the states Bj racing has the parts and in England trails and trial. Are just two of the many. And there is Ebay. Quote Link to comment Share on other sites More sharing options...
pschrauber Posted March 17, 2013 Report Share Posted March 17, 2013 Boost bottle !!!, E P I C, very interesting and contemporary indeed. How did you measure / calculate the bottle, do you have used the Information given from Trialsport in the beginning 80's: or do you have used any other ressource? Have you any practical advice to tell ! Looking forward for any news on that. 1 Quote Link to comment Share on other sites More sharing options...
andy.t Posted March 17, 2013 Report Share Posted March 17, 2013 Tyjay, try and get the stock engine running before adding any performance parts. The points according to Haynes should be .35mm or 0.014 if thats what your Mini is set at then its more luck than anything else, they are hard to set with any great accuracy so if you dont mind spending £200 go for electronic. I cant agree withthe piston comment other than yes it would be nice to have one with the correct port holes in the piston, mine is from a IT175 and for what ever reason it works well. So for starters get those points set spot on, if that dont improve things have a look at the carb, whilst talking about the carb, if the lube system has been dumped and your running on premix make sure the hole where the oil was injected on the carb has been blocked. A mate of mine had been messing around with his bike for ages and I pointed out that he was pulling in air from the lube hole. 1 Quote Link to comment Share on other sites More sharing options...
tyjay Posted March 17, 2013 Author Report Share Posted March 17, 2013 Cheers for that advice ill check that hole is blocked up I set the points to 15 thou so ill try 14 but tbh when I say flat it just seems like I have to rev it a lot in low gear to get any thing out of it but then again that could be due to weak spark Nd engine struggling under load ? Correct maybe . But I could do with a comparison or ago on sum ones ty175 to see if mine is flat or if that's just how they are ! And what the hell is a boost bottle no one has explained lol ? And is there any other exhausts and manifolds that fit other than the ty after market ones ? Quote Link to comment Share on other sites More sharing options...
2stroke4stroke Posted March 17, 2013 Report Share Posted March 17, 2013 I don't know what your other experience is but a TY 175 will feel flat compared to a more modern bike. I've ridden a 175 that was tuned by an expert and it was still flat, certainly compared to my TY 200 but I've no idea how the conversion was done or what other mods were made eg porting. I daresay if boost bottles had worked we would still be using them on current bikes. Quote Link to comment Share on other sites More sharing options...
dombush Posted March 17, 2013 Report Share Posted March 17, 2013 (edited) tjay a boost bottle is a simple chamber that is connected to the intake port of the engine. So called because the chamber was often a small plastic "bottle" shaped item. The "bottle" was connected to the void between the carb and the reed valve. The idea was that atomised fuel/air mixture was drawn up into this chamber when the rider shuts off the throttle. The inertia of the intake charge fills the bottle and is released when the rider opens up again. Often found on 1980's Yamaha's as i believe they had a patent on the idea. See this diagram for clarity.. http://www.google.co...9QEwAw&dur=2698 2-stroke engine design has changed significantly since then.. Powervalves (not on trials bikes), improved carbs, reed valves, ignition, porting has rendered this design less necessary. Dom Edited March 17, 2013 by dombush Quote Link to comment Share on other sites More sharing options...
andy.t Posted March 18, 2013 Report Share Posted March 18, 2013 Tyjay, just had another thought from what you last said. Have you got the correct sprocket set up ? if its still got road gearing on it (mine did have) then that could be your problem. Most people around my neck of the woods use a 12 front(11 works but bike does rear up a bit) and a 51 rear sprocket (428 chain). Quote Link to comment Share on other sites More sharing options...
tyjay Posted March 18, 2013 Author Report Share Posted March 18, 2013 Very good point on sprocket ill try and have look so my ideas for now is set te points correctly I'm going to lighten the flywheel slightly as its free for me ! Check carb oil feeds been blocked properly and ill do a sprocket n chain change n give it a go sounds about right because when I'm going from trial to trial along dirt track it's quick but I'm in really low gears to get up a hill even first sum times so seems like it could be a sprocket problem ! Ill still get a new boysen reeds will I need to change pilot jet ! And what does it involve to change the read cage ? To the rd350 one ? Quote Link to comment Share on other sites More sharing options...
andy.t Posted March 18, 2013 Report Share Posted March 18, 2013 TYjay, the RD350 inlet rubber is all that you change, the reed cage will not fit. The advantage as mentioned is that it centralisers the inlet hole to the hole in the reed cage. It also then has a connection point to connect a boost bottle ( dont go there yet ) You will have to shave off a couple of bits of rubber to make it sit flat. If you can get hold of a new reed cage then that would be a bonus, they do come up on ebay from time to time and more so in the states. There are a few guys that sell new replica RD rubbers on ebay but they are sold in pairs for about £30, just get a mate to but one and share the cost Quote Link to comment Share on other sites More sharing options...
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