I rebuilt the top end on my Brothers Suzuki GT750 but certain area's were a two man job. The cylinder head, being cast in one, and being water cooled, had to be hit with a wooden mallet, to free it off. Beware of a single nut on the kickstart side, just in front of the water pump. Once loose, the barrel could be gently lifted, but stuff rags in the open crankcases in case old bits of piston rings fall down into the cases. We had the block re-bored, and new oversized pistons and rings. But, check the rings, off the pistons, at the top of the bores, because if they pinch, they will need to be filed, otherwise they will break. It was a two man job fitting the cylinder block over the new pistons. Remember to use new gaskets both top and bottom. We filled the radiator back up with coolant, but it began to leak around the cylinder block. Use a torque wrench and tighten them up in a diagonal sequence. One tip a guy at a work shop said was, warm the engine up without any coolant in, then after the engine has cooled, re- tighten the cylinder head bolts, and no more leaks.
That bike is a credit to you. Oh, the fun I had on mine : I had to go on the bus to pick mine up from a milkman in Dewsbury. Saturday lunchtime I arrived. I couldn't believe the smooth racing gearbox (I was progressing from a CZ 125 - which have a huge sloppy movement that declutches). Shorty afterwards my uncle also bought one : we did the Lake district (300 miles in the day), we also did Mastiles Lane (off road trail) from Kilnsey Crag to Malham Tarn. Looking back at 61, I can honestly say no bike brought me more pleasure.
I owned a YDS7 as a 16 year old (before the law changed in UK). Loved riding that bike. 2-strokes, -- the sound of them, the smell and the performance, can't be beat. Thanks for the video, I found it very interesting and it brought back many pleasant memories.
My friend had a yds7 and I had a gt250 and we used to race each other silly 🤣🤣great times. And your bike is lovely 👍great memories thanks for posting ✌🏻
It was one of those in that colour in The Old Kent Road 50 odd years ago it all started for me as a 7 yr old! My first Real desire, unfulfilled! it wasn’t until I saw the 350 LC that I felt that same “I must have one” desire It was £1199, I think 200 notes dearer than the 250, and my first experience of H.P. Thanks for triggering the memory fella 👍
Thanks for sharing this brings back so many memories of my first rd 250 just after the yds7 they still look great your bike looks fantastic mate 👍 enjoy
Brings back memories. my YDS7 was a bit earlier then yours, J reg and a slightly lighter colour. I never touched the engine so it's interesting to see this video. Your bike looks and sounds great.
Hi mcmerchanic , I've just purchased the exact same YDS7 in mint condition, it was my first bike as a 17 year in 1972 so i just had to buy it, all is good apart from the speedometer is not working any advise would be appreciated as you seem to be very knowledgeable on this old classic motorcycle, you really turned that bike around, really enjoyed your vlog and content, 👍
@@mcmechanic864 Oh Yes the uk fender is longer made for the number plate to go on top we was the only place in the world that had that, all the others had a shorter fender as on the brochures.
Hi Again, Yes, they do come up for sale now and again. My problem is there are several different components to the damper and I'm not sure how they all fit together or fit to the bike? There is a diagram in my Haynes but it's not very clear and they don't describe the damper in detail. Any help appreciated 🙂 Thanks, Nigel
@@nigelparkin5264 Ok, go on cmsnl.com, search for YDS7 and you’ll find the parts book, find your steering damper and make a note of all the part numbers you need,then put them part numbers one by one into Google, and you should come up with images of what you want and you can work it out from there. You’ll even get eBay results on Google. Hope that helps, that’s all I would do 🙂
So my buddy and I are working on his 72 DS7 again. Would you happen to know what voltages/ohms to test the ignition coils to see if they're bad or not? I can't find the info anywhere online
Just search TH-cam for "motorcycle ignition coil testing" all coils have roughly the same readings, it will be obvious if they are bad if they are a long way out. Good luck
I was lucky, the seat base was in very good original condition, I only had to repaint it. The cove is off eBay, here is a link: www.ebay.co.uk/itm/Motorcycle-seat-foam-cover-and-strap-complete-kit-Yamaha-YR5-DS7-/203183551384?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=710-127635-2958-0
@@johnbell3962 Yeah... 😁 I've rebuilt hundreds of engines over the last 40 years as a motorcycle mechanic.... The YDS7 has only done 30 miles since I done this video, it will be checked 😉
Sounds and looks lovely. Did it rattle before the rebore? I have rebuilt a GT250B with new standard size pistons , new little ends and rings, crank rebuilt, honing the original bores, but it still rattles top end. Im thinking piston slap.
My friend has one of these and we keep having an issue with it misfiring and revving up after the misfire. The carbs have been rebuilt and tuned to factory specs, but it won't run properly. Has new head gaskets and exhaust gaskets. Just seems like the pre mix oil isn't getting to the piston. Any ideas?
Ignition coils can fail on these, if the ignition is left on without the engine running for longer than 10-15 minutes it will damage it or destroy it. Also try new plug caps. 🙂
@@mcmechanic864 it's also running pretty hot, so I'm wondering if the oil isn't getting mixed with the fuel properly. Hope it isn't damaged the piston rings. I'll tear it down again and double check everything
I'm sorry I don't know 🤔 I gave the tank to a painter and he just copied the colour to paint the headlight and side panels, I was pleased with the result 🙂
Owned one of these in Sarasota Florida ca1975, one of the best bikes I ever owned. So much fun to ride!
I rebuilt the top end on my Brothers Suzuki GT750 but certain area's were a two man job.
The cylinder head, being cast in one, and being water cooled, had to be hit with a wooden
mallet, to free it off. Beware of a single nut on the kickstart side, just in front of the water
pump. Once loose, the barrel could be gently lifted, but stuff rags in the open crankcases
in case old bits of piston rings fall down into the cases. We had the block re-bored, and
new oversized pistons and rings. But, check the rings, off the pistons, at the top of the
bores, because if they pinch, they will need to be filed, otherwise they will break. It was
a two man job fitting the cylinder block over the new pistons. Remember to use new
gaskets both top and bottom. We filled the radiator back up with coolant, but it began
to leak around the cylinder block. Use a torque wrench and tighten them up in a diagonal
sequence. One tip a guy at a work shop said was, warm the engine up without any coolant
in, then after the engine has cooled, re- tighten the cylinder head bolts, and no more leaks.
Very nice motorcycle, especially the brake steering damper is an engineering wonder of simplicity and practicality.
I had one of this model 3 weeks before I got married in 1971, never missed a beat.
That bike is a credit to you.
Oh, the fun I had on mine : I had to go on the bus to pick mine up from a milkman in Dewsbury.
Saturday lunchtime I arrived. I couldn't believe the smooth racing gearbox (I was progressing from a CZ 125 - which have a huge sloppy movement that declutches).
Shorty afterwards my uncle also bought one : we did the Lake district (300 miles in the day), we also did Mastiles Lane (off road trail) from Kilnsey Crag to Malham Tarn.
Looking back at 61, I can honestly say no bike brought me more pleasure.
Great story 👍
Also, that twin-leading-shoe brake was magnificent.
My next bike was a GT380 with a disc...... I said more Hail Marys than soft Mick.
I owned a YDS7 as a 16 year old (before the law changed in UK). Loved riding that bike. 2-strokes, -- the sound of them, the smell and the performance, can't be beat. Thanks for the video, I found it very interesting and it brought back many pleasant memories.
Glad you enjoyed it 🙂
Dude, that is soooo sweet!
Thanks for the video. Memories, had one back in 1976. Loved it!
My friend had a yds7 and I had a gt250 and we used to race each other silly 🤣🤣great times. And your bike is lovely 👍great memories thanks for posting ✌🏻
Thanks 👍
It was one of those in that colour in The Old Kent Road 50 odd years ago it all started for me as a 7 yr old! My first Real desire, unfulfilled! it wasn’t until I saw the 350 LC that I felt that same “I must have one” desire
It was £1199, I think 200 notes dearer than the 250, and my first experience of H.P.
Thanks for triggering the memory fella 👍
Thanks for sharing this brings back so many memories of my first rd 250 just after the yds7 they still look great your bike looks fantastic mate 👍 enjoy
Thanks 👍🙂
Brings back memories. my YDS7 was a bit earlier then yours, J reg and a slightly lighter colour. I never touched the engine so it's interesting to see this video. Your bike looks and sounds great.
Great video sir. Never tried the ‘unattached piston in the barrel’ method before, top tip!!!
Thanks Patrick, yeah works well
Top quality video 👍
Hi mcmerchanic , I've just purchased the exact same YDS7 in mint condition, it was my first bike as a 17 year in 1972 so i just had to buy it, all is good apart from the speedometer is not working any advise would be appreciated as you seem to be very knowledgeable on this old classic motorcycle, you really turned that bike around, really enjoyed your vlog and content, 👍
The first thing to check is the cable, is it rotating ? If it is then it's the speedo head
That is a very nice UK YDS7 and you have the UK front mudguard too well done.
Thanks for your comment 👍
I didn't actually know the mudguard was different in the UK, what is the difference?
@@mcmechanic864 Oh Yes the uk fender is longer made for the number plate to go on top we was the only place in the world that had that, all the others had a shorter fender as on the brochures.
@@yamaha7237 oh ok, I knew the UK mudguard had the holes ready drilled for the number plate bu didn't realise it was longer
Great job sir it sounds sweet as a nut ! 👍🏻🏴
Thank you 👍
Great video.
Amaizing bike
Hi There, does your bike have the steering damper fitted please. I'm not sure how to fit one to my bike.
Thanks 😊 Nigel
Yes, a steering damper is fitted as standard to this model, you would have to go on eBay and see if you can find a secondhand one. It should all fit
Hi Again,
Yes, they do come up for sale now and again. My problem is there are several different components to the damper and I'm not sure how they all fit together or fit to the bike?
There is a diagram in my Haynes but it's not very clear and they don't describe the damper in detail.
Any help appreciated 🙂
Thanks, Nigel
@@nigelparkin5264 Ok, go on cmsnl.com, search for YDS7 and you’ll find the parts book, find your steering damper and make a note of all the part numbers you need,then put them part numbers one by one into Google, and you should come up with images of what you want and you can work it out from there. You’ll even get eBay results on Google. Hope that helps, that’s all I would do 🙂
How to sync the carburetors can u help me I have a rd350
So my buddy and I are working on his 72 DS7 again. Would you happen to know what voltages/ohms to test the ignition coils to see if they're bad or not? I can't find the info anywhere online
Just search TH-cam for "motorcycle ignition coil testing" all coils have roughly the same readings, it will be obvious if they are bad if they are a long way out. Good luck
Thanks for the upload very informative,one question ,I've just brought a r5 350and the seat is shot where did you purchase your cover and base .thanks
I was lucky, the seat base was in very good original condition, I only had to repaint it. The cove is off eBay, here is a link:
www.ebay.co.uk/itm/Motorcycle-seat-foam-cover-and-strap-complete-kit-Yamaha-YR5-DS7-/203183551384?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=710-127635-2958-0
@@mcmechanic864 much appreciated thanks for info
Great looking and running Yamaha. Did you have to retorque the head bolts after first warm up?
No but I probably will check them over the winter, I have the fuel tank off at the moment so a good time to check 👍
I know the heads can come loose after heating and cooling sometimes with negative results and torque should be checked.
@@johnbell3962 Yeah... 😁
I've rebuilt hundreds of engines over the last 40 years as a motorcycle mechanic....
The YDS7 has only done 30 miles since I done this video, it will be checked 😉
Sounds and looks lovely. Did it rattle before the rebore? I have rebuilt a GT250B with new standard size pistons , new little ends and rings, crank rebuilt, honing the original bores, but it still rattles top end. Im thinking piston slap.
Yes I think so, you'll almost certainly need a rebore and oversized pistons, mine did sound rattly before....not now 👍
If the replacement pistols are forged they may rattle until properly warmed up.
@@johnbell3962 I don't think genuine pistons are forged
@@mcmechanic864 mine where Original Suzuki. I don't think they are forged.
You guys are correct about genuine pistons and are preferred. Wisecos are forged and may a rattle a bit until warm.
My friend has one of these and we keep having an issue with it misfiring and revving up after the misfire. The carbs have been rebuilt and tuned to factory specs, but it won't run properly. Has new head gaskets and exhaust gaskets. Just seems like the pre mix oil isn't getting to the piston. Any ideas?
Ignition coils can fail on these, if the ignition is left on without the engine running for longer than 10-15 minutes it will damage it or destroy it.
Also try new plug caps. 🙂
@@mcmechanic864 it's also running pretty hot, so I'm wondering if the oil isn't getting mixed with the fuel properly. Hope it isn't damaged the piston rings. I'll tear it down again and double check everything
Possible air leak somewhere, bad crank seals? Timing needs to
be checked also.
@@johnbell3962 we ended up finding out one of the floats was sticking
Glad to hear! Thanks.
What is the actual gold colour
I'm sorry I don't know 🤔 I gave the tank to a painter and he just copied the colour to paint the headlight and side panels, I was pleased with the result 🙂
Great looking bike ...top notch 👍