In­side the belly of the beast

1985 Yamaha RD350 YPVS

Practical Sportsbikes (UK) - - On Our Bench -

It’s ju­nior Tyler’s first ever big bike strip­down – with Gary and Al on hand for ‘friendly’ ad­vice

In the last grip­ping in­stal­ment of Project Pow­er­valve, we dis­cov­ered that some amount of chaos had been wrought by ro­dents in the air­box. This re­sulted in some­thing that looked like gra­nola in the bot­tom of the air­box, carbs and reed blocks and as far as we could guess, even be­yond that. Lift­ing the bar­rels re­vealed a re­bore and new pis­tons were in or­der and there was no ques­tion that the en­gine would have to come down to get the crank out as one of the big-ends was graunchy.

Tyler was keen to re­move the en­gine from the frame him­self then strip it down with min­i­mal in­ter­ven­tion. Gary and Al were more than happy to stand around drink­ing tea and cof­fee while of­fer­ing the odd bit of ad­vice of vary­ing use­ful­ness. It was Tyler’s first-ever en­gine strip. “Get stuck in,” said an en­cour­ag­ing G, “but don’t be afraid to ask for a hand if you need it.”

With the gear­box plug out to let the oil drain – we’d got rid of the coolant last month when we lifted the bar­rels – first off was the sprocket cover, re­veal­ing yet more mouse muesli nestling

at the bot­tom of the cast­ing. Tyler got the spring link off with pli­ers, mirac­u­lously leav­ing ev­ery­one’ s eye­sight in taccr at, nak np din th–as tc ra an pd.o th net he anci en tu nlub ed chain w er eric gohnts,tigh­neef dr et so­ht­shteu ff scrap pile.

Off with the oil pump cover and out with the ca­ble then Tyler with­drew the pump it­self. Out with the en­gine mount­ing bolts and the tie-rod bolts un­der the en­gine, a quick check round in case any fas­ten­ers or elec­tri­cal con­nec­tors had been missed and Tyler called on Al to help lift the en­gine out of the frame.

With the mo­tor on the bench the time for truth as to ex­actly what might be re­quired, and more im­por­tantly what it all might cost, drew closer. At the start of op­er­a­tions, Tyler had been adamant that he would be us­ing only gen­uine parts through­out the re­build. This had caused some raised eye­brows with Gary and Al, who are rather tighter of wal­let. As the strip pro­gressed, Tyler’s re­solve in this area started to shift slightly.

“There are some ar­eas where orig­i­nal equip­ment is def­i­nitely the way to go,” said Gary be­tween mouth­fuls of Maxwell House (milk, one sugar), “head gas­kets cer­tainly, other gas­kets prefer­ably, crank seals prob­a­bly, al­though these days there is some good af­ter­mar­ket stuff out there and rep­utable two-stroke spe­cial­ists won’t sell you rub­bish, even if you in­sist on it.” Alan was of a sim­i­lar opin­ion: “I al­ways use OE head gas­kets but hap­pily use af­ter­mar­ket stuff for the other gas­kets and seals if avail­able.”

Tyler cracked on with the strip as he con­tem­plated his op­tions. Soon the clutch cover was off af­ter a ju­di­cious blow or two from the hide ham­mer. Gary re­quested a penny, not for any­one’s thoughts or to send af­ter all that in­stant cof­fee but rather to lock the pri­mary gears with while the clutch was un­done. With the pres­sure plate and fric­tion and steel plates re­moved then the clutch tab washer chis­elled back, Tyler de­ployed the air wrench on the nut and the one for the pri­mary gears too. “Didn’t need a clutch hold­ing tool then,” he mused. Al­though he might have found one use­ful in the ab­sence of a com­pres­sor.

Off with the gen­er­a­tor cover and the fly­wheel’s nut, again made easy by the im­pact wrench, and it was a con­ven­tion de­fy­ing ‘lefty tighty and righty loosey’ mo­ment for Tyler us­ing the left-hand thread fly­wheel ex­trac­tor tool, the sat­is­fac­tion of which never grows tire­some.

TYLER HAD BEEN ADAMANT HE’D BE US­ING ONLY GEN­UINE PARTS. THIS CAUSED RAISED EYE­BROWS WITH TIGHTWADS GARY AND AL. AS THE STRIP PRO­GRESSED TYLER’S RE­SOLVE IN THIS AREA STARTED TO SHIFT

With the fly­wheel off and sta­tor and pick­ups re­moved, Tyler was get­ting close to split­ting the cases. First the screwed in bear­ing re­tainer un­der the clutch bas­ket had to be re­moved – it bridges both of the hor­i­zon­tally split cases, Tyler bor­rowed one of Pete O’dell’s T-bar JIS screw­drivers to en­sure safe re­moval.

Next Tyler cracked off all the crankcase bolts top and bot­tom. “Yamaha are very good at hid­ing those un­der some un­ex­pected places,” said Gary, prompt­ing Tyler to check then check again be­fore spin­ning out all of the bolts. “Where shall I hit the cases to get them apart?” asked Tyler, wav­ing the mal­let dan­ger­ously close to a thin part of the top case. “Not there,” yelled G be­fore guid­ing Tyler to the more sub­stan­tial ar­eas of the cast­ings. Tyler was less keen to smack his own cases hard than Gary was, so of­fer­ing him the ham­mer, G re­vealed the gas­ket line with one well-placed tap.

That meant Tyler could at last lift the cases to re­veal just how much work would need to be done. We’d al­ready es­tab­lished the need for a crank re­build, a view only com­pounded by more mouse may­hem in the bot­tom of the left side of the case un­der the fly­wheels when the crank was lifted out. The crank seals were more like bake­lite than rub­ber too. Gary spun the mains to demon­strate just how shot they were. Even against the back­ground noise in The Mo­tor­cy­cle Works work­shop (never any­thing less than a buzzing hive of cease­less ac­tiv­ity) you could hear them grum­bling, a lit­tle like Gary when asked to MOT a knack­ered Chi­nese 125.

There was plenty of good news as far as the gear­box went. Even the se­lec­tor forks were in far bet­ter con­di­tion than you’d ex­pect to find them on a hooli­gan favourite like the 350 YPVS.

So a crank and top-end re­build should be the big­gest of Tyler’s is­sues get­ting the bike back on the road. Not at all bad for a bike that was a to­tally un­known quan­tity un­til its in­au­gu­ral strip­down at the hands of Tyler.

Happy?

“I just can’t wait to ride it,” said the pro­tege as he headed off with his spare parts shop­ping list.

THANKS TO The Mo­tor­cy­cle Works 01733 578883, the­mo­tor­cy­cle­works.co.uk

“WHERE SHALL I HIT THE CASES TO GET THEM APART?” ASKED TYLER, WAV­ING THE MAL­LET DAN­GER­OUSLY CLOSE TO A THIN PART OF THE TOP CASE. “NOT THERE,” YELLED G GUID­ING TYLER

It’s a big mo­ment for the wee fella

Just as well it came out – all knack­ered save the gear­box

A beam­ing face where once there was a tired en­gine

Where it all starts to get a bit more se­ri­ous

All his own work – top ef­fort Tyler. So far so good

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