jon v8 Posted July 2, 2008 Report Share Posted July 2, 2008 Finally,I have got round to staring a project I've been thinking about for ages.A long time ago I bought a totally stripped TY175 - because it was there. Then started looking around for an XT225 Serrow engine to go in it,couldnt find one.Last week I took one in to cover a bad debt.My idea is an alternative to a TLR,(which look nice but I could never ride them any sense)but with the added bonus of electric start. Tonight I cut the frame around enough to get the XT motor in and started sussing out measurements for engine mounts etc.Its a bit of a squeeze but it will work,and so far looks like it will make a nice bike.Anyway reason for posting is that the biggest problem I can see so far is that the very large CV carb that the XT was fitted with is no way going to fit as the top of the carb is geeting on 3" in dia - much too big.Borrowed a carb off one of my TY250's and that will just about sit right with a new angled manifold. So, anyone have any experience with going back to a conventional carb on a small 4 stroke that had the cv type carb.Going to have to make a petrol tank too,but I'm not worried about that,more so the carb as it ran so sweetly - none of the stutter/stopping issues that my TLR250 frustrated me so much with. Cheers in advance,Jon. Quote Link to comment Share on other sites More sharing options...
andy m Posted July 2, 2008 Report Share Posted July 2, 2008 (edited) There is a TY mono about with a Serow motor in, remember seeing it in tmx. Re the carb, you may be able to go smaller than ty carb. There was a TL about with a RS 200 motor in that ran well using a XR75 carb. Maybe SR/ XT 125 or similar. You are not after top end after all. Just a thought. edit. how about a carb off a tys Scorpa 125 /175f ?? Ttr 200 maybe if they are slide ?? Edited July 2, 2008 by bo drinker Quote Link to comment Share on other sites More sharing options...
t-shock 250 Posted July 2, 2008 Report Share Posted July 2, 2008 This sounds like an interesting project, any pics? Quote Link to comment Share on other sites More sharing options...
nzralphy Posted July 3, 2008 Report Share Posted July 3, 2008 Kool project. I think CV carbs were mostly used to avoid the 'Snapping the throttle open flat spot'. A fuel pump carb does the same but uses way more gas. If you run a rich idle and a small cut-away slide you will also reduce the flat spot - but idle could be a bit rough. Actually if you run a smallish carb you'll get less hesitation. Two stroke carbs can be used but use slightly different needle jet system so you'll have to mess with most of the jets and are often larger than the equivalent 4T carb size. Sorry if the above is useless ramblings. Ralph Quote Link to comment Share on other sites More sharing options...
jon v8 Posted July 3, 2008 Author Report Share Posted July 3, 2008 Ta for the ideas,had a look again this morning and I reckon the best thing is to cut about 1/2 of the top tube out and weld a pair of tubes back on letting the original CV carb sit in between.Most of the bottom of the tank will need chopping out to accomodate the cyl head so I'll just need to chop a bit more out. I reckon it will be easier to do the frame than fiddle with carbs. When I got the Serrow it had been sat for at least 2 years,but a sniff of fresh fuel and it ran absolutely spot on,even making it run down so low it was lurching you could open the throttle and it would just pick up - ten times better than either the TLR or RTL that I had back in the 80's.NZralphy - I think you are right,not rambling ! So the CV carb will stay. Sorry cant do pics at the moment,I'm in the throws of deciding what camera to buy - I'll get some on as soon as I can. Quote Link to comment Share on other sites More sharing options...
andyrothers Posted July 4, 2008 Report Share Posted July 4, 2008 You can get secondhand carbs off the later yamaha 125 engines - TTR, XT etc which are identical to the scorpa - I think the road bike versions are different (more complicated?)- I've bought a spare for my scorpa and prior to that ran one on my 200 honda with the same jetting as the 125, mixture was fine and ran much better (cleaner response) than the standard honda carb but is different fitment (goes into rubber manifold) rather than the honda flange. Paid somewhere in the region of 15-20 quid from memory for the carb. Andy Quote Link to comment Share on other sites More sharing options...
matty Posted July 5, 2008 Report Share Posted July 5, 2008 Hi, Thought this might be of interest to you if you needed to sort out a pipe for your project ? http://www.trailridinginkent.co.uk/cgi-bin...;num=1209065804 Good Luck Matt. Quote Link to comment Share on other sites More sharing options...
jon v8 Posted December 6, 2008 Author Report Share Posted December 6, 2008 Now the building work on my cottage is finished I can start work on my bikes again.The frame is almost finished,and its on to stuff like fuel tank,airbox and exhaust.I am going to make it all from sheet or tube aluminium,(Nice length of 3" tube left over from the guttering for the centre box and silencer !) but am I going to run into problems at MOT time ? Because the bike is registered it would be useful to have a daylight MOT as there are a couple of trials so close to me I could ride to them.(Plus it is a useful extra bit of transport) If I make up the exhaust it wont have any BS markings on it and I seem to remember this is necessary.Am I right,and if so what can I do to get around it? Quote Link to comment Share on other sites More sharing options...
totalshell Posted December 6, 2008 Report Share Posted December 6, 2008 markings not required on exhaust.. what you dont want is something that says '' not for road use'' or ''track use only'' Quote Link to comment Share on other sites More sharing options...
jon v8 Posted December 6, 2008 Author Report Share Posted December 6, 2008 Thats a relief ! I'm planning to semi flatten a section of the 3" tube to make a silencer,so it wont have any writing on it.I'm getting a digital camera for Christmas so I'll post up some piccys as soon as I get going with it. Quote Link to comment Share on other sites More sharing options...
andy m Posted December 6, 2008 Report Share Posted December 6, 2008 Why not have xmas early and get the camera sorted and get those pics up. Besides xmas is for kids. Go on you know you want to. Quote Link to comment Share on other sites More sharing options...
jon v8 Posted December 7, 2008 Author Report Share Posted December 7, 2008 Why not have xmas early and get the camera sorted and get those pics up. Besides xmas is for kids. Go on you know you want to. At a slightly ripe age of 43,I still am child like - according to domestic staff. I'm waiting for the sales after Christmas for an even bigger bargain.Hopefully over the holiday I'll be able to find time to really get stuck into it and have more to take pics of,hoping to be able to ride it in the 09 Bath series and esp the Dartmoor 2 day. Quote Link to comment Share on other sites More sharing options...
jon v8 Posted June 19, 2011 Author Report Share Posted June 19, 2011 Well at last there is progress.... I decided its been too long sitting gathering dust so I've had a good go at it this weekend and built it up to a rolling bike.Nowhere near finished,but its got me enthused to get on with it.Balancing on it in the workshop makes it feel really small and suprisingly well balanced. The idea is to do a dry build so I can do a good test ride on it then strip and paint it.Dartmoor here I come ! Quote Link to comment Share on other sites More sharing options...
copemech Posted June 20, 2011 Report Share Posted June 20, 2011 HolyJesus, I oft wondered about that! Keep it up, matey! Quote Link to comment Share on other sites More sharing options...
jon v8 Posted June 29, 2011 Author Report Share Posted June 29, 2011 It runs !! I cancelled a couple of jobs this week to give me time to sort a few things out.Then I just got carried away with working on the Xty, I've sorted out the electrics,(Well the ignition anyway)starting is by jump leads from a car battery.It has no brakes yet,nor air filter etc so plenty more to do. First impressions are good,its centre of gravity feels low and it steers nicely.Despite the slow action Domino throttle its still too abrupt so that wants slowing down.My calcs for the gearing were about right,first is nice and low but second is a tad faster than I'd like - I guess there has to be a compromise somewhere unless you have a works team behind you. Looks fairly positive for Dartmoor in september. Quote Link to comment Share on other sites More sharing options...
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