Post by chuckhahn on Sept 15, 2016 19:14:00 GMT -5
Im new here and have emailed Argo many times some years ago when I first picked up a 73 TX750. It had the burnt cam and journals due to the top end problems commonly seen due to the foaming of the oil as was found to be the case way back in the day.
I replaced the cam and got new cam blocks which ran me close to 400 dollars. I have ridden it a handful of times but am so leary of oil foaming and ruining the top end again. I have read some things about adding a defoamer agent to the oil such as was used in high RPM diesel engines. Fleet and Navistar were a few names mentioned.
Wednesday I went to the local semi truck supply house and asked if they had any of the Navistar stuff and they told me it was NLA and they didnt have any defoaming agents there for sale. I have read a good deal on adding silicone oil to hydraulics and some machine oils to prevent oil aeration.
So this brings me to my question. Does anyone know of any information on using silicone oil in regular engine oils to defoam it, and secondly does anyone know of a defoamer on the market specifically for use in engine oils?? I sure would like to ride the bike with some feelings of confidence Im not tearing the top end apart again.
Post by chuckhahn on Sept 15, 2016 19:22:53 GMT -5
Heres a video of the bike just after redoing the top end. It was pretty windy that day but its running very nicely. Sorry for the wind noise. Take note of how much work I put into polishing and repainting the engine based on the pics in the post further down.....quite a difference from the starting point
Last Edit: Sept 16, 2016 19:34:14 GMT -5 by chuckhahn
Post by scrambler on Sept 16, 2016 17:39:42 GMT -5
Unfortunately the video doesn`t work for me, but your bike looks great! It`s interesting what you are saying about these cam issues. Did you use synthetic oil? What makes you think that it was the aeration? Did you have the extended sump and oil cooler? I still have doubts about these aeration issues, and I agree with Argo that the deep sump is rather overrated. Normally there should not be any oil in the sump as the scavanging pump has a higher capacity than the other, that`s the point of dry sump oil circulation. Adding silicone oil seems not to be an appropriate way of solving this issue, there has to be some failure in your engine. Modifying the oil passages as Argo did on his bike makes much more sense to me, although I don`t understand it completely, see above.
Post by chuckhahn on Sept 16, 2016 19:28:44 GMT -5
The aeration issue was well discussed in the October 1972 issue of Cycle World and the engineers came up with the counter balances were whipping the oil into a froth. The article was written by the man that was directly responsible for the recall and distribution of the oil coolers and sumps. Granted they didnt have the oil technology we have today back in the 70s. This is why I was pondering the defoamer to quickly deaerate the oil in the sump so as to not make the pump loose prime.
The oil running down the cam chain tunnel is running smack in to the counter balancers and getting whipped up. There is a small amount of oil that collects in the pan far as i understand all I have read, and this oil cant be full of bubbles.
Im the second owner of this bike and i have the original title dated May 21, 1973 from the original owner. Its a bone stock 73..so no sump extention. There also wasnt an oil cooler which was part of Yamahas fix for 73 models. the recall was to add the sump collar AND an oil cooler. these fixes were then standard for the 74 model but by then the damage to its reputatiuon had done the bike in.
Have you tried clicking on the picture in my post to see if it inks you to the video?? Heres some pics as we got it home from the guys house...niow mind you this bike had a little over 9,000 original miles and had been in the shed since 1986.
Last Edit: Sept 16, 2016 20:04:12 GMT -5 by chuckhahn
Post by chuckhahn on Sept 16, 2016 19:30:31 GMT -5
Try this link.... This was just after I got the carbs rebuilt and actually got it running again. If you listen closely you can hear the top end clatter going on.
Last Edit: Sept 16, 2016 19:36:35 GMT -5 by chuckhahn
Post by scrambler on Sept 17, 2016 20:11:54 GMT -5
Now both links work. You have a very nice looking bike! Mine is exactly the same, not in such pristine condition though. Yes, I think i can hear the clanking. How many miles did it take to end up with the same issue with camshaft? I`m the 2nd owner of mine as well, and based on the history of the bike it got a new camshaft at 800 miles in warranty, after that there were no issues with the cam, and it has 35k miles on it now. I don`t know what they changed when they replaced the camshaft, but apparently that solved the problem. I`m gonna take apart the engine soon and perhaps figure it out.
Post by scrambler on Sept 18, 2016 23:42:02 GMT -5
Nice collection, Chuck. I got the same stuff with mine mostly, also the original owner documented everything in the back of the owner`s manualfrom the very beginning when he had purchased it in 73 till the current mileage.
I really appreciate this kind of lasting enthusiasm.
Post by morgan osullivan on Apr 25, 2020 9:24:18 GMT -5
Hi all. As an owner of a 73 TX750 in Dublin can anyone point me to an individual in Germany/Holland who undertakes engine upgrade and re-build. Its time for the ol girl to see the quiet Irish roads again. Thank you.
This forum looks quite abandoned, so I bring up something that might initiate some discussion
Finally I managed to get the paperwork done on my bike, it took me a couple of months and several rounds to the DMV, but now I`m the legal owner with a pink slip with my name on. So, as the restoration/renewal makes sense now, I`d like to explore around what to expect. My bike is a `73 year with no modifications besides the oil cooler and the automotive filter. I read a couple of articles here and there and I learnt that this year version suffered of oil pressure problems due to the bubbles caused by the balance shaft that yamaha solved by adding a deeper sump to the bike from `74 on. What I don`t understand is, if this engine has a dry sump system, shouldn`t it be free of oil in the sump? And if it`s not, because, say the scavanging is not perfect for some reason, the foamy oil is going to the oil tank anyway, so the bubbles would have time to come out.. Still, at most forums replacing the sump to the deeper version is highly recommended. However, my bike made 35000 miles with the original sump and the engine seems untouched (not much compression left, though). So, what is the general thinking about this? Is it rather the failure of the scavanging that causes the problem when coincides with the shallow sump? In other words, if the scavanging works fine, it does not matter which type of sump I have on the bike? Let me know what you guys think.
Hi all. As an owner of a 73 TX750 in Dublin can anyone point me to an individual in Germany/Holland who undertakes engine upgrade and re-build. Its time for the ol girl to see the quiet Irish roads again. Thank you.
I would like to add this old issue with oil circulation is possible something whereby extreme running at high rpm with rubbish oils caused problems , why anyone would buy a twin and run it at hight rpm knowing it's natural imbalance I don't know that's why 4 cylinder bikes completed the TT races when most twins failed , although the 270deg is clever ,I use to design engines btw , these old japanese engines need to be treated with some respect considering rpm quality oils and how hot they get , most japanese bike makers we're learning on the job to make bikes faster than British bikes