1975 yamaha DT250B help

[zombieguy12]

Hey guys new to the forum, and have a couple questions i bought this dt250 as a project / beginner bike and its been a little more of a project lol

anyways when i got it, it would sputter but never started so i checked the compression and got 30, tore the head apart and figures, rings are fried, spun the drive assembly and everything spun great, except for a bearing, i assumed crank, but no play just a scratching/whine.

Took it in to my local shop to have the case pulled apart and new bearings installed, it turns out it was the countershaft bearing, they told me that they thought it could be saved by cleaning it up so thats what we did, but we went ahead and installed new crank bearings, and put in all new seals,

At the same time i ordered and installed a new wiseco 2nd over kit (it had already been bored once, but i had it done again because like i said the rings were fried)

I got them both back put it all together and was missing the check ball in the clutch i got one at fastenal, and the auto-lube system had been disconnected prior but withought a block off plate, i have since made a block off, and blocked off the carb

My question to you is, when i picked up the lower end he recommended no break in process?(again new bearings)and suggested 20-50 castrol, is it just me or is that really thick?

And also now that ive disconnected the auto lube the throttle cable seems REALLY loose unless i hold the autolube cable in place, anything i need to do with this

 

[jpmobius]

Are you talking about the lower end and trans, or the top end (or both) ? There is not much to do with the bottom end, as it is an all roller bearing assembly. It is freshly assembled though, and you might think changing out the oil after a short period of time. I personally do so after 100 miles or so just to have clean oil after a rebuild, but opinions vary. 20 -50 is fine, I use Rotela, or a dedicated 2-stroke trans lube. The main consideration is that the DT uses a wet clutch, and some oils adversely impact the performance. For me, seems like the shift cam is often a weak link seemingly helped by something thicker like the Rotela, but it's an opinion and not very scientific. Breaking in the top end seems to have two camps. Slow and easy, gradually increasing the severity of use and max rpm over several hundred miles. Most factory specs are like this. I am in the other camp, wanting to get rapid ring seating before polishing or glazing the cylinder walls so I warm up fresh engines completely and run them hard under load several times and consider it done. I have always had very good strong results, but again, opinions vary, and I am careful with the tuning combination and run rich on fuel, rich on oil, and very conservative on ignition timing until all the parts make friends with each other. There is a ton of talk on the interweb about this, so you will have to make your own choice. Any number of things can be the cable issue, but that bike has a 1 into 2 cable, and if you don't run the oil pump, I suggest you swap it for a single cable direct to the carb. without the autolube cable, the doubler will be unequally loaded and may give trouble. Highly recommend getting a pump and using it. They are extremely reliable.

 

[mattham28]

Hello all, I am new to this website and posting on a what ever this thing is. But I bought a 78 dt400 with NO fenders, lights, side covers, oil tank, gauges, muffler, original front wheel. The plus side is I gave $50 for it. What after market parts can I get to fit on the bike by spending the least amount of money? also does anyone know if these gasket sets are worth the money?

http://www.ebay.com/itm/77-78-Yamaha-DT400-Engine-gaskets-Set-New-Reproduction-CI-DT400GS-/161243434822?pt=Motorcycles_Parts_Accessories&hash=item258adb8f46&vxp=mtr

Thanks everyone